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.

	HDMI audio properties:
	- #sound-dai-cells: <0> or <1>. <0> if only i2s or spdif pin
	   is wired, <1> if the both are wired. HDMI audio is
	   configured only if this property is found.
	- sil,i2s-data-lanes: Array of up to 4 integers with values of 0-3
	   Each integer indicates which i2s pin is connected to which
	   audio fifo. The first integer selects i2s audio pin for the
	   first audio fifo#0 (HDMI channels 1&2), second for fifo#1
	   (HDMI channels 3&4), and so on. There is 4 fifos and 4 i2s
	   pins (SD0 - SD3). Any i2s pin can be connected to any fifo,
	   but there can be no gaps. E.g. an i2s pin must be mapped to
	   fifo#0 and fifo#1 before mapping a channel to fifo#2. Default
	   value is <0>, describing SD0 pin beiging routed to hdmi audio
	   fifo #0.
	- clocks: phandle and clock specifier for each clock listed in
           the clock-names property
	- clock-names: "mclk"
	   Describes SII902x MCLK input. MCLK can be used to produce
	   HDMI audio CTS values. This property follows
	   Documentation/devicetree/bindings/clock/clock-bindings.txt
	   consumer binding.

	If HDMI audio is configured the sii902x device becomes an I2S
	and/or spdif audio codec component (e.g a digital audio sink),
	that can be used in configuring a full audio devices with
	simple-card or audio-graph-card binding. See their binding
	documents on how to describe the way the sii902x device is
	connected to the rest of the audio system:
	Documentation/devicetree/bindings/sound/simple-card.yaml
	Documentation/devicetree/bindings/sound/audio-graph-card.txt
	Note: In case of the audio-graph-card binding the used port
	index should be 3.

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>;

		#sound-dai-cells = <0>;
		sil,i2s-data-lanes = < 0 1 2 >;
		clocks = <&mclk>;
		clock-names = "mclk";

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

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