Refactor VND7050AJ sensor configuration to eliminate redundancy

- Create centralized sensor multiplexer node (vnd7050aj_mux) with shared configuration
- Consolidate ADC channel, GPIO pins, and reference voltage in single location
- Update sensor bindings to reference centralized mux via sensor-mux property
- Add channel-based sensor selection using mux-channel property (0-3)
- Refactor ADC sensor library to use centralized GPIO and channel control
- Update valve library to use new vnd7050aj_mux node reference
- Eliminate duplicate ADC/GPIO definitions between voltage and current sensors
- Ensure configuration consistency and prevent mismatched settings

Benefits:
- Single source of truth for VND7050AJ hardware configuration
- Impossible to have inconsistent GPIO/ADC settings between sensors
- Simplified maintenance and scalability for additional sensors
- Clean channel-based multiplexer selection interface

software/apps/slave_node/dts/bindings/adc/custom,motor-current.yaml

@@ -1,16 +1,13 @@
-description: Custom motor current measurement with GPIO control
+# Custom motor current sensor binding
+description: Motor current sensor using VND7050AJ multiplexer
 
 compatible: "custom,motor-current"
 
 properties:
-  io-channels:
-    type: phandle-array
+  sensor-mux:
+    type: phandle
     required: true
-    description: ADC channel for current measurement
-
-  io-channel-names:
-    type: string-array
-    description: Names for the ADC channels
+    description: Reference to the VND7050AJ sensor multiplexer node
 
   current-sense-resistor-mohm:
     type: int
@@ -19,30 +16,17 @@ properties:
 
   amplifier-gain:
     type: int
+    required: false
     default: 1
     description: Current sense amplifier gain
 
-  reference-mv:
+  mux-channel:
     type: int
-    default: 3300
-    description: ADC reference voltage in millivolts
-
-  sen-gpios:
-    type: phandle-array
     required: true
-    description: GPIO to enable/disable the current measurement sensor
-
-  s0-gpios:
-    type: phandle-array
-    required: true
-    description: GPIO for multiplexer control bit 0
-
-  s1-gpios:
-    type: phandle-array
-    required: true
-    description: GPIO for multiplexer control bit 1
+    description: Multiplexer channel number (0-3) for this sensor
 
   measurement-delay-ms:
     type: int
+    required: false
     default: 10
-    description: Delay in milliseconds after setting GPIOs before ADC measurement
+    description: Delay in milliseconds after GPIO setup before measurement

software/apps/slave_node/dts/bindings/adc/custom,supply-voltage.yaml

@@ -1,63 +1,26 @@
-description: Custom supply voltage measurement with GPIO control
+# Custom supply voltage sensor binding
+description: Supply voltage sensor using VND7050AJ multiplexer
 
 compatible: "custom,supply-voltage"
 
 properties:
-  io-channels:
-    type: phandle-array
+  sensor-mux:
+    type: phandle
     required: true
-    description: ADC channel for voltage measurement
-
-  io-channel-names:
-    type: string-array
-    description: Names for the ADC channels
+    description: Reference to the VND7050AJ sensor multiplexer node
 
   voltage-divider-ratio:
     type: int
     required: true
-    description: Voltage divider ratio for scaling
+    description: Voltage divider ratio for scaling measurements
 
-  reference-mv:
+  mux-channel:
     type: int
-    default: 3300
-    description: ADC reference voltage in millivolts
-
-  sen-gpios:
-    type: phandle-array
     required: true
-    description: GPIO to enable/disable the voltage measurement sensor
-
-  s0-gpios:
-    type: phandle-array
-    required: true
-    description: GPIO for multiplexer control bit 0
-
-  s1-gpios:
-    type: phandle-array
-    required: true
-    description: GPIO for multiplexer control bit 1
+    description: Multiplexer channel number (0-3) for this sensor
 
   measurement-delay-ms:
     type: int
-    default: 10
-    description: Delay in milliseconds after setting GPIOs before ADC measurement
-
-  sen-gpios:
-    type: phandle-array
-    required: true
-    description: GPIO for SEN (Sense Enable) pin
-
-  s0-gpios:
-    type: phandle-array
-    required: true
-    description: GPIO for S0 (Select 0) pin
-
-  s1-gpios:
-    type: phandle-array
-    required: true
-    description: GPIO for S1 (Select 1) pin
-
-  measurement-delay-ms:
-    type: int
-    default: 10
-    description: Delay in milliseconds after setting control pins before ADC reading
+    required: false
+    default: 5
+    description: Delay in milliseconds after GPIO setup before measurement

software/apps/slave_node/dts/bindings/adc/vnd7050aj,sensor-mux.yaml

@@ -0,0 +1,50 @@
+# VND7050AJ Sensor Multiplexer binding
+description: VND7050AJ sensor multiplexer for ADC channel selection
+
+compatible: "vnd7050aj,sensor-mux"
+
+properties:
+  io-channels:
+    type: phandle-array
+    required: true
+    description: ADC channel phandle and specifier for sensor input
+
+  io-channel-names:
+    type: string-array
+    required: true
+    description: Names for the ADC channels
+
+  reference-mv:
+    type: int
+    required: true
+    description: ADC reference voltage in millivolts
+
+  sen-gpios:
+    type: phandle-array
+    required: true
+    description: GPIO for sensor enable (SEN pin)
+
+  s0-gpios:
+    type: phandle-array
+    required: true
+    description: GPIO for multiplexer select bit 0 (S0 pin)
+
+  s1-gpios:
+    type: phandle-array
+    required: true
+    description: GPIO for multiplexer select bit 1 (S1 pin)
+
+  in0-gpios:
+    type: phandle-array
+    required: false
+    description: GPIO for valve input 0 control (IN0 pin)
+
+  in1-gpios:
+    type: phandle-array
+    required: false
+    description: GPIO for valve input 1 control (IN1 pin)
+
+  rst-gpios:
+    type: phandle-array
+    required: false
+    description: GPIO for reset control (RST pin)