dt-bindings: iio: adc: ti,adc084s021 yaml conversion

Simple conversion.

Added the #io-channel-cells optional property to allow for consumer
bindings if appropriate on a given board.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Mårten Lindahl <martenli@axis.com>
Link: https://lore.kernel.org/r/20200809111753.156236-8-jic23@kernel.org

Documentation/devicetree/bindings/iio/adc/ti,adc084s021.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/ti,adc084s021.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments ADC084S021 ADC
+
+maintainers:
+  - Mårten Lindahl <martenli@axis.com>
+
+description: |
+  8 bit ADC with 4 channels
+
+properties:
+  compatible:
+    const: ti,adc084s021
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency: true
+
+  vref-supply:
+    description: External reference, needed to establish input scaling
+
+  spi-cpol: true
+  spi-cpha: true
+
+  "#io-channel-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - vref-supply
+  - spi-cpol
+  - spi-cpha
+
+additionalProperties: false
+
+examples:
+  - |
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+            compatible = "ti,adc084s021";
+            reg = <0>;
+            vref-supply = <&adc_vref>;
+            spi-cpol;
+            spi-cpha;
+            spi-max-frequency = <16000000>;
+            #io-channel-cells = <1>;
+        };
+    };
+...

Documentation/devicetree/bindings/iio/adc/ti-adc084s021.txt

-* Texas Instruments' ADC084S021
-
-Required properties:
- - compatible        : Must be "ti,adc084s021"
- - reg               : SPI chip select number for the device
- - vref-supply       : The regulator supply for ADC reference voltage
- - spi-cpol          : Per spi-bus bindings
- - spi-cpha          : Per spi-bus bindings
- - spi-max-frequency : Per spi-bus bindings
-
-Example:
-adc@0 {
-	compatible = "ti,adc084s021";
-	reg = <0>;
-	vref-supply = <&adc_vref>;
-	spi-cpol;
-	spi-cpha;
-	spi-max-frequency = <16000000>;
-};