[media] dt-bindings: Add a binding for Mediatek Video Processor

Add a DT binding documentation of Video Processor Unit for the
MT8173 SoC from Mediatek.

Signed-off-by: Andrew-CT Chen <[e-mail]>
Signed-off-by: Tiffany Lin <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

Documentation/devicetree/bindings/media/mediatek-vpu.txt

···
+* Mediatek Video Processor Unit
+
+Video Processor Unit is a HW video controller. It controls HW Codec including
+H.264/VP8/VP9 Decode, H.264/VP8 Encode and Image Processor (scale/rotate/color convert).
+
+Required properties:
+  - compatible: "mediatek,mt8173-vpu"
+  - reg: Must contain an entry for each entry in reg-names.
+  - reg-names: Must include the following entries:
+    "tcm": tcm base
+    "cfg_reg": Main configuration registers base
+  - interrupts: interrupt number to the cpu.
+  - clocks : clock name from clock manager
+  - clock-names: must be main. It is the main clock of VPU
+
+Optional properties:
+  - memory-region: phandle to a node describing memory (see
+    Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt)
+    to be used for VPU extended memory; if not present, VPU may be located
+    anywhere in the memory
+
+Example:
+	vpu: vpu@10020000 {
+		compatible = "mediatek,mt8173-vpu";
+		reg = <0 0x10020000 0 0x30000>,
+		      <0 0x10050000 0 0x100>;
+		reg-names = "tcm", "cfg_reg";
+		interrupts = <GIC_SPI 166 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&topckgen TOP_SCP_SEL>;
+		clock-names = "main";
+	};