Documentation: DT: Add documentation for ti,opa362 bindings

OPA362 analog video amplifier

Required properties:

- compatible: "ti,opa362"

- enable-gpios: enable/disable output gpio

Required node:

- Video port 0 for opa362 input

- Video port 1 for opa362 output

Example:

tv_amp: opa362 {

	compatible = "ti,opa362";

	enable-gpios = <&gpio1 23 0>;  /* GPIO to enable video out amplifier */

	ports {

		#address-cells = <1>;

		#size-cells = <0>;

		port@0 {

			reg = <0>;

			opa_in: endpoint@0 {

				remote-endpoint = <&venc_out>;

			};

		};

		port@1 {

			reg = <1>;

			opa_out: endpoint@0 {

				remote-endpoint = <&tv_connector_in>;

			};

		};

	};

};