ps8622-bridge bindings

Required properties:
	- compatible: "parade,ps8622" or "parade,ps8625"
	- reg: first i2c address of the bridge
	- sleep-gpios: OF device-tree gpio specification for PD_ pin.
	- reset-gpios: OF device-tree gpio specification for RST_ pin.

Optional properties:
	- lane-count: number of DP lanes to use
	- use-external-pwm: backlight will be controlled by an external PWM
	- video interfaces: Device node can contain video interface port
			    nodes for panel according to [1].
	- dual-channel: boolean. if it exists, enable dual channel mode

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

Example:

&i2c4 {
	status = "okay";

	ps8625: ps8625@48 {
		compatible = "parade,ps8625";
		reg = <0x48>;
		sleep-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
		reset-gpios = <&gpio2 4 GPIO_ACTIVE_HIGH>;
		lane-count = <2>;
		use-external-pwm;

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

			port@0 {
				reg = <0>;

				ps8625_in_edp: endpoint {
					remote-endpoint = <&edp_out_ps8625>;
				};
			};

			port@1 {
				reg = <1>;

				ps8625_out_panel: endpoint {
					remote-endpoint = <&panel_in_ps8625>;
				};
			};
		};
	};
};
