dt-bindings: usb: add documentation for typec port controller(TCPCI)

TCPCI(Typec port cotroller interface) binding

---------------------------------------------

Required properties:

- compatible:       should be set one of following:

		    - "nxp,ptn5110" for NXP USB PD TCPC PHY IC ptn5110.

- reg:              the i2c slave address of typec port controller device.

- interrupt-parent: the phandle to the interrupt controller which provides

                    the interrupt.

- interrupts:       interrupt specification for tcpci alert.

Required sub-node:

- connector: The "usb-c-connector" attached to the tcpci chip, the bindings

  of connector node are specified in

  Documentation/devicetree/bindings/connector/usb-connector.txt

Example:

ptn5110@50 {

	compatible = "nxp,ptn5110";

	reg = <0x50>;

	interrupt-parent = <&gpio3>;

	interrupts = <3 IRQ_TYPE_LEVEL_LOW>;

	usb_con: connector {

		compatible = "usb-c-connector";

		label = "USB-C";

		data-role = "dual";

		power-role = "dual";

		try-power-role = "sink";

		source-pdos = <PDO_FIXED(5000, 2000, PDO_FIXED_USB_COMM)>;

		sink-pdos = <PDO_FIXED(5000, 2000, PDO_FIXED_USB_COMM)

			     PDO_VAR(5000, 12000, 2000)>;

		op-sink-microwatt = <10000000>;

		ports {

			#address-cells = <1>;

			#size-cells = <0>;

			port@1 {

				reg = <1>;

				usb_con_ss: endpoint {

					remote-endpoint = <&usb3_data_ss>;

				};

			};

		};

	};

};