dt-bindings: media: mediatek: mdp3: add component FG for MT8195

Add the fundamental hardware configuration of component FG,
which is controlled by MDP3 on MT8195.
Signed-off-by: Moudy Ho <moudy.ho@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <zangelogioacchino.delregno@collabora.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Documentation/devicetree/bindings/media/mediatek,mdp3-fg.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/media/mediatek,mdp3-fg.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MediaTek Media Data Path 3 Film Grain
+
+maintainers:
+  - Matthias Brugger <matthias.bgg@gmail.com>
+  - Moudy Ho <moudy.ho@mediatek.com>
+
+description:
+  Film Grain (FG) is a Media Data Path 3 (MDP3) component used to add
+  the film grain according to the AOMedia Video 1 (AV1) standard.
+
+properties:
+  compatible:
+    enum:
+      - mediatek,mt8195-mdp3-fg
+
+  reg:
+    maxItems: 1
+
+  mediatek,gce-client-reg:
+    description:
+      The register of display function block to be set by gce. There are 4 arguments,
+      such as gce node, subsys id, offset and register size. The subsys id that is
+      mapping to the register of display function blocks is defined in the gce header
+      include/dt-bindings/gce/<chip>-gce.h of each chips.
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    items:
+      items:
+        - description: phandle of GCE
+        - description: GCE subsys id
+        - description: register offset
+        - description: register size
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - mediatek,gce-client-reg
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/mt8195-clk.h>
+    #include <dt-bindings/gce/mt8195-gce.h>
+
+    display@14002000 {
+        compatible = "mediatek,mt8195-mdp3-fg";
+        reg = <0x14002000 0x1000>;
+        mediatek,gce-client-reg = <&gce1 SUBSYS_1400XXXX 0x2000 0x1000>;
+        clocks = <&vppsys0 CLK_VPP0_MDP_FG>;
+    };