dt-bindings: gpio: convert rk3328-grf-gpio.txt to YAML

Current dts files with RK3328 GRF 'gpio' nodes are manually verified.
In order to automate this process rk3328-grf-gpio.txt has to be
converted to YAML.

Rename 'grf-gpio' nodename to 'gpio'.
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Documentation/devicetree/bindings/gpio/rockchip,rk3328-grf-gpio.txt

-Rockchip RK3328 GRF (General Register Files) GPIO controller.
-
-In Rockchip RK3328, the output only GPIO_MUTE pin, originally for codec mute
-control, can also be used for general purpose. It is manipulated by the
-GRF_SOC_CON10 register in GRF. Aside from the GPIO_MUTE pin, the HDMI pins can
-also be set in the same way.
-
-Currently this GPIO controller only supports the mute pin. If needed in the
-future, the HDMI pins support can also be added.
-
-Required properties:
-- compatible: Should contain "rockchip,rk3328-grf-gpio".
-- gpio-controller: Marks the device node as a gpio controller.
-- #gpio-cells: Should be 2. The first cell is the pin number and
-  the second cell is used to specify the gpio polarity:
-    0 = Active high,
-    1 = Active low.
-
-Example:
-
-	grf: syscon@ff100000 {
-		compatible = "rockchip,rk3328-grf", "syscon", "simple-mfd";
-
-		grf_gpio: grf-gpio {
-			compatible = "rockchip,rk3328-grf-gpio";
-			gpio-controller;
-			#gpio-cells = <2>;
-		};
-	};
-
-Note: The grf_gpio node should be declared as the child of the GRF (General
-Register File) node. The GPIO_MUTE pin is referred to as <&grf_gpio 0>.

Documentation/devicetree/bindings/gpio/rockchip,rk3328-grf-gpio.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/rockchip,rk3328-grf-gpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Rockchip RK3328 General Register Files GPIO controller
+
+description:
+  The Rockchip RK3328 General Register File (GRF) outputs only the
+  GPIO_MUTE pin, originally for codec mute control, but it can also be used
+  for general purpose. It is manipulated by the GRF_SOC_CON10 register.
+  If needed in the future support for the HDMI pins can also be added.
+  The GPIO node should be declared as the child of the GRF node.
+
+  The GPIO_MUTE pin is referred to in the format
+
+  <&grf_gpio 0 GPIO_ACTIVE_LOW>
+
+  The first cell is the pin number and
+  the second cell is used to specify the GPIO polarity
+    0 = Active high
+    1 = Active low
+
+maintainers:
+  - Heiko Stuebner <heiko@sntech.de>
+
+properties:
+  compatible:
+    const: rockchip,rk3328-grf-gpio
+
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 2
+
+required:
+  - compatible
+  - gpio-controller
+  - "#gpio-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    grf_gpio: gpio {
+      compatible = "rockchip,rk3328-grf-gpio";
+      gpio-controller;
+      #gpio-cells = <2>;
+    };