dt-bindings:iio:adc:dlg,da9150-gpadc yaml conversion

This is a small part of an MFD so perhaps ultimately it makes more
sense to document it with that MFD binding rather than separately.

In the meantime it's a straightforward conversion from txt to yaml.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Link: https://lore.kernel.org/r/20200909175946.395313-13-jic23@kernel.org

Documentation/devicetree/bindings/iio/adc/da9150-gpadc.txt

-Dialog Semiconductor DA9150 IIO GPADC bindings
-
-Required properties:
-- compatible: "dlg,da9150-gpadc" for DA9150 IIO GPADC
-- #io-channel-cells: Should be set to <1>
-  (See Documentation/devicetree/bindings/iio/iio-bindings.txt for further info)
-
-For further information on GPADC channels, see device datasheet.
-
-
-Example:
-
-	gpadc: da9150-gpadc {
-		compatible = "dlg,da9150-gpadc";
-		#io-channel-cells = <1>;
-	};

Documentation/devicetree/bindings/iio/adc/dlg,da9150-gpadc.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/dlg,da9150-gpadc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Dialog Semiconductor DA9150 IIO GPADC
+
+maintainers:
+  - Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
+
+description:
+  This patch adds support for general purpose ADC within the
+  DA9150 Charger & Fuel-Gauge IC.
+
+properties:
+  compatible:
+    const: dlg,da9150-gpadc
+
+  "#io-channel-cells":
+    const: 1
+
+required:
+  - compatible
+  - "#io-channel-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    adc {
+        compatible = "dlg,da9150-gpadc";
+        #io-channel-cells = <1>;
+    };
+...