dt-bindings: iio: accel: kionix,kxsd9 yaml conversion.

Convert and flesh out a bit the binding docs for this simple 3 axis
accelerometer.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/iio/accel/kionix,kxsd9.txt

-Kionix KXSD9 Accelerometer device tree bindings
-
-Required properties:
- - compatible: 		should be set to "kionix,kxsd9"
- - reg:			i2c slave address
-
-Optional properties:
- - vdd-supply:		The input supply for VDD
- - iovdd-supply:	The input supply for IOVDD
- - interrupts:		The movement detection interrupt
- - mount-matrix:	See mount-matrix.txt
-
-Example:
-
-kxsd9@18 {
-	compatible = "kionix,kxsd9";
-	reg = <0x18>;
-	interrupt-parent = <&foo>;
-	interrupts = <57 IRQ_TYPE_EDGE_FALLING>;
-	iovdd-supply = <&bar>;
-	vdd-supply = <&baz>;
-};

Documentation/devicetree/bindings/iio/accel/kionix,kxsd9.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/accel/kionix,kxsd9.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Kionix KXSD9 Accelerometer
+
+maintainers:
+  - Jonathan Cameron <jic23@kernel.org>
+
+description: |
+  3 axis 12 bit accelerometer with +-8G range on all axes. Also has a
+  12 bit auxiliary ADC channel. Interface is either SPI or I2C.
+
+properties:
+  compatible:
+    const: kionix,kxsd9
+
+  reg:
+    maxItems: 1
+
+  vdd-supply: true
+  iovdd-supply: true
+
+  interrupts:
+    maxItems: 1
+
+  mount-matrix:
+    description: an optional 3x3 mounting rotation matrix.
+
+required:
+  - compatible
+  - reg
+
+examples:
+  - |
+    # include <dt-bindings/interrupt-controller/irq.h>
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        accel@18 {
+            compatible = "kionix,kxsd9";
+            reg = <0x18>;
+            iovdd-supply = <&iovdd>;
+            vdd-supply = <&vdd>;
+            interrupts = <57 IRQ_TYPE_EDGE_FALLING>;
+            mount-matrix = "-0.984807753012208", "0",  "-0.173648177666930",
+                           "0",                  "-1", "0",
+                           "-0.173648177666930", "0",  "0.984807753012208";
+        };
+    };
+  - |
+    # include <dt-bindings/interrupt-controller/irq.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        accel@0 {
+            compatible = "kionix,kxsd9";
+            reg = <0>;
+            spi-max-frequency = <10000000>;
+        };
+    };
+...