dt-bindings: gpio: realtek: Add realtek,rtd-gpio

Add the device tree bindings for the Realtek DHC(Digital Home Center)
RTD SoCs GPIO controllers.
Signed-off-by: Tzuyi Chang <tychang@realtek.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Documentation/devicetree/bindings/gpio/realtek,rtd-gpio.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright 2023 Realtek Semiconductor Corporation
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/realtek,rtd-gpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Realtek DHC GPIO controller
+
+maintainers:
+  - Tzuyi Chang <tychang@realtek.com>
+
+description:
+  The GPIO controller is designed for the Realtek DHC (Digital Home Center)
+  RTD series SoC family, which are high-definition media processor SoCs.
+
+properties:
+  compatible:
+    enum:
+      - realtek,rtd1295-misc-gpio
+      - realtek,rtd1295-iso-gpio
+      - realtek,rtd1315e-iso-gpio
+      - realtek,rtd1319-iso-gpio
+      - realtek,rtd1319d-iso-gpio
+      - realtek,rtd1395-iso-gpio
+      - realtek,rtd1619-iso-gpio
+      - realtek,rtd1619b-iso-gpio
+
+  reg:
+    items:
+      - description: GPIO controller registers
+      - description: GPIO interrupt registers
+
+  interrupts:
+    items:
+      - description: Interrupt number of the assert GPIO interrupt, which is
+                     triggered when there is a rising edge.
+      - description: Interrupt number of the deassert GPIO interrupt, which is
+                     triggered when there is a falling edge.
+
+  gpio-ranges: true
+
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 2
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - gpio-ranges
+  - gpio-controller
+  - "#gpio-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    gpio@100 {
+      compatible = "realtek,rtd1319d-iso-gpio";
+      reg = <0x100 0x100>,
+            <0x0 0xb0>;
+      interrupt-parent = <&iso_irq_mux>;
+      interrupts = <19>, <20>;
+      gpio-ranges = <&pinctrl 0 0 82>;
+      gpio-controller;
+      #gpio-cells = <2>;
+    };