dt-bindings: gpio: wcd934x: Add bindings for gpio

Qualcomm Technologies Inc WCD9340/WCD9341 Audio Codec has integrated
gpio controller to control 5 gpios on the chip. This patch adds
required device tree bindings for it.
Signed-off-by: NSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: NRob Herring <robh@kernel.org>
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20200107130844.20763-2-srinivas.kandagatla@linaro.orgSigned-off-by: NLinus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/gpio/qcom,wcd934x-gpio.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/qcom,wcd934x-gpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: WCD9340/WCD9341 GPIO controller
+
+maintainers:
+  - Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
+
+description: |
+  Qualcomm Technologies Inc WCD9340/WCD9341 Audio Codec has integrated
+  gpio controller to control 5 gpios on the chip.
+
+properties:
+  compatible:
+    enum:
+      - qcom,wcd9340-gpio
+      - qcom,wcd9341-gpio
+
+  reg:
+    maxItems: 1
+
+  gpio-controller: true
+
+  '#gpio-cells':
+    const: 2
+
+required:
+  - compatible
+  - reg
+  - gpio-controller
+  - "#gpio-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    wcdgpio: gpio@42 {
+        compatible = "qcom,wcd9340-gpio";
+        reg = <0x042 0x2>;
+        gpio-controller;
+        #gpio-cells = <2>;
+    };
+
+...