sii902x HDMI bridge bindings

Required properties:
	- compatible: "sil,sii9022"
	- reg: i2c address of the bridge

Optional properties:
	- interrupts: describe the interrupt line used to inform the host 
	  about hotplug events.
	- reset-gpios: OF device-tree gpio specification for RST_N pin.

Optional subnodes:
	- video input: this subnode can contain a video input port node
	  to connect the bridge to a display controller output (See this
	  documentation [1]).

[1]: Documentation/devicetree/bindings/media/video-interfaces.txt

Example:
	hdmi-bridge@39 {
		compatible = "sil,sii9022";
		reg = <0x39>;
		reset-gpios = <&pioA 1 0>;
		ports {
			#address-cells = <1>;
			#size-cells = <0>;

			port@0 {
				reg = <0>;
				bridge_in: endpoint {
					remote-endpoint = <&dc_out>;
				};
			};
		};
	};