dt-bindings: iio: adc: lltc,ltc2497 yaml conversion.

Very simple binding for this i2c device with a reference supply.

Added the #io-channel-cells property to allow for consumers.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Michael Hennerich <michael.hennerich@analog.com>
Link: https://lore.kernel.org/r/20200809111753.156236-5-jic23@kernel.org

Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/lltc,ltc2497.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Linear Technology / Analog Devices LTC2497 ADC
+
+maintainers:
+  - Michael Hennerich <michael.hennerich@analog.com>
+
+description: |
+  16bit ADC supporting up to 16 single ended or 8 differential inputs.
+  I2C interface.
+
+properties:
+  compatible:
+    const:
+      lltc,ltc2497
+
+  reg: true
+  vref-supply: true
+  "#io-channel-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - vref-supply
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@76 {
+            compatible = "lltc,ltc2497";
+            reg = <0x76>;
+            vref-supply = <&ltc2497_reg>;
+            #io-channel-cells = <1>;
+        };
+    };
+...

Documentation/devicetree/bindings/iio/adc/ltc2497.txt

-* Linear Technology / Analog Devices LTC2497 ADC
-
-Required properties:
- - compatible: Must be "lltc,ltc2497"
- - reg: Must contain the ADC I2C address
- - vref-supply: The regulator supply for ADC reference voltage
-
-Example:
-	ltc2497: adc@76 {
-		compatible = "lltc,ltc2497";
-		reg = <0x76>;
-		vref-supply = <&ltc2497_reg>;
-	};