ITE it66121 HDMI bridge bindings

Required properties:
	- compatible : "ite,it66121".
	- reg : I2C address, use 0x4c or 0x4d
	- vcn33-supply : Digital Supply Voltage (3.3V)
	- vcn18-supply : I/O Supply Voltage (1.8V)
	- vrf12-supply : Analog Supply Voltage (1.2V)
	- interrupts: interrupt specifier of INT pin
	- reset-gpios: gpio specifier of RESET pin (active low)
	- pclk-dual-edge: dual edge clocking
	- video interfaces: Device node can contain one video interface port
			    node for HDMI encoder according to [1].

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

Example:

	it66121hdmitx: it66121hdmitx@4c {
		compatible = "ite,it66121";
		pinctrl-names = "default";
		pinctrl-0 = <&ite_pins_default>;
		vcn33-supply = <&mt6358_vcn33_wifi_reg>;
		vcn18-supply = <&mt6358_vcn18_reg>;
		vrf12-supply = <&mt6358_vrf12_reg>;
		reset-gpios = <&pio 160 GPIO_ACTIVE_LOW>;
		interrupt-parent = <&pio>;
		interrupts = <4 IRQ_TYPE_LEVEL_LOW>;
		reg = <0x4c>;
		pclk-dual-edge;

		port {
			it66121_in: endpoint {
				remote-endpoint = <&dpi_out>;
			};
		};
	};