dt-bindings:iio:adc:nuvoton,nau7802 yaml conversion

A simple conversion from txt file to yaml.  I added the #io-channel-cells
property as optional to allow the channels of this ADCs to be used
to provide services to other drivers, for example if an analog
accelerometer is connected.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20200909175946.395313-8-jic23@kernel.org

Documentation/devicetree/bindings/iio/adc/nuvoton,nau7802.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/nuvoton,nau7802.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Nuvoton NAU7802 I2c Analog to Digital Converter (ADC)
+
+maintainers:
+  - Alexandre Belloni <alexandre.belloni@bootlin.com>
+  - Maxime Ripard <mripard@kernel.org>
+
+properties:
+  compatible:
+    const: nuvoton,nau7802
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  nuvoton,vldo:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Internal reference voltage in millivolts to be configured.
+    minimum: 2400
+    maximum: 4500
+
+  "#io-channel-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        nau7802@2a {
+            compatible = "nuvoton,nau7802";
+            reg = <0x2a>;
+            nuvoton,vldo = <3000>;
+        };
+    };
+...

Documentation/devicetree/bindings/iio/adc/nuvoton-nau7802.txt

-* Nuvoton NAU7802 Analog to Digital Converter (ADC)
-
-Required properties:
-  - compatible: Should be "nuvoton,nau7802"
-  - reg: Should contain the ADC I2C address
-
-Optional properties:
-  - nuvoton,vldo: Internal reference voltage in millivolts to be
-    configured valid values are between 2400 mV and 4500 mV.
-  - interrupts: IRQ line for the ADC. If not used the driver will use
-    polling.
-
-Example:
-adc2: nau7802@2a {
-	compatible = "nuvoton,nau7802";
-	reg = <0x2a>;
-	nuvoton,vldo = <3000>;
-};