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.
	- i2s-fifo-routing: Array of exactly 4 integers indicating i2s
	  pins for audio fifo routing. First integer defines routing to
	  fifo 0 and second to fifo 1, etc. Integers can be filled with
	  definitions from: include/dt-bindings/sound/sii902x-audio.h
	  The available definitions are:
	  - ENABLE_BIT:	enable this audio fifo
	  - CONNECT_SD#: route audio input from SD0, SD1, SD2, or SD3 i2s
			 data input pin
	  - LEFT_RIGHT_SWAP_BIT: swap i2s input channels for this fifo
	  I2S HDMI audio is configured only if this property is found.
	- clocks: describes SII902x MCLK input. MCLK is used to produce
	  HDMI audio CTS values. This property is required if
	  "i2s-fifo-routing"-property is present. This property follows
	  Documentation/devicetree/bindings/clock/clock-bindings.txt
	  consumer binding.

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>;

		i2s-fifo-routing = <
			(ENABLE_BIT|CONNECT_SD0)
			0
			0
			0
		>;
		clocks = <&mclk>;

		ports {
			#address-cells = <1>;
			#size-cells = <0>;

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