dt-bindings:iio:adc:holt,hi8435 yaml conversion

Very simple binding.  I've changed the example to use the node
name threshold-detector@0 as sensor@0 seemed too generic.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Vladimir Barinov <vladimir.barinov@cogentembedded.com>
Link: https://lore.kernel.org/r/20200909175946.395313-18-jic23@kernel.org

Documentation/devicetree/bindings/iio/adc/hi8435.txt

-Holt Integrated Circuits HI-8435 threshold detector bindings
-
-Required properties:
- - compatible: should be "holt,hi8435"
- - reg: spi chip select number for the device
-
-Recommended properties:
- - spi-max-frequency: definition as per
-		Documentation/devicetree/bindings/spi/spi-bus.txt
-
-Optional properties:
- - gpios: GPIO used for controlling the reset pin
-
-Example:
-sensor@0 {
-	compatible = "holt,hi8435";
-	reg = <0>;
-	gpios = <&gpio6 1 0>;
-
-	spi-max-frequency = <1000000>;
-};

Documentation/devicetree/bindings/iio/adc/holt,hi8435.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/holt,hi8435.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Holt Integrated Circuits HI-8435 SPI threshold detector
+
+maintainers:
+  - Vladimir Barinov <vladimir.barinov@cogentembedded.com>
+
+description: |
+  Datasheet: http://www.holtic.com/documents/427-hi-8435_v-rev-lpdf.do
+
+properties:
+  compatible:
+    const: holt,hi8435
+
+  reg:
+    maxItems: 1
+
+  gpios:
+    description:
+       GPIO used for controlling the reset pin
+    maxItems: 1
+
+  spi-max-frequency: true
+
+  "#io-channel-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        threshold-detector@0 {
+            compatible = "holt,hi8435";
+            reg = <0>;
+            gpios = <&gpio6 1 0>;
+            spi-max-frequency = <1000000>;
+        };
+    };
+...