dt-bindings: display: mediatek: Add binding for HDMIv2 DDC

Add a binding for the Display Data Channel (DDC) IP in MediaTek
SoCs with version 2 HDMI TX IP.

Reviewed-by: Rob Herring (Arm) <[e-mail]>
Reviewed-by: CK Hu <[e-mail]>
Signed-off-by: AngeloGioacchino Del Regno <[e-mail]>
Link: https://patchwork.kernel.org/project/dri-devel/patch/[e-mail]/
Signed-off-by: Chun-Kuang Hu <[e-mail]>

Documentation/devicetree/bindings/display/mediatek/mediatek,mt8195-hdmi-ddc.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/mediatek/mediatek,mt8195-hdmi-ddc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MediaTek HDMI MT8195 series HDMI Display Data Channel (DDC)
+
+maintainers:
+  - AngeloGioacchino Del Regno <[e-mail]>
+  - CK Hu <[e-mail]>
+
+properties:
+  compatible:
+    oneOf:
+      - const: mediatek,mt8195-hdmi-ddc
+      - items:
+          - const: mediatek,mt8188-hdmi-ddc
+          - const: mediatek,mt8195-hdmi-ddc
+
+  clocks:
+    maxItems: 1
+
+  power-domains:
+    maxItems: 1
+
+required:
+  - compatible
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    hdmi {
+        hdmi_ddc: i2c {
+            compatible = "mediatek,mt8195-hdmi-ddc";
+            clocks = <&clk26m>;
+        };
+    };
+...