dt-bindings: add bindings for USB physical connector

USB Connector

=============

USB connector node represents physical USB connector. It should be

a child of USB interface controller.

Required properties:

- compatible: describes type of the connector, must be one of:

    "usb-a-connector",

    "usb-b-connector",

    "usb-c-connector".

Optional properties:

- label: symbolic name for the connector,

- type: size of the connector, should be specified in case of USB-A, USB-B

  non-fullsize connectors: "mini", "micro".

Required nodes:

- any data bus to the connector should be modeled using the OF graph bindings

  specified in bindings/graph.txt, unless the bus is between parent node and

  the connector. Since single connector can have multpile data buses every bus

  has assigned OF graph port number as follows:

    0: High Speed (HS), present in all connectors,

    1: Super Speed (SS), present in SS capable connectors,

    2: Sideband use (SBU), present in USB-C.

Examples

--------

1. Micro-USB connector with HS lines routed via controller (MUIC):

muic-max77843@66 {

	...

	usb_con: connector {

		compatible = "usb-b-connector";

		label = "micro-USB";

		type = "micro";

	};

};

2. USB-C connector attached to CC controller (s2mm005), HS lines routed

to companion PMIC (max77865), SS lines to USB3 PHY and SBU to DisplayPort.

DisplayPort video lines are routed to the connector via SS mux in USB3 PHY.

ccic: s2mm005@33 {

	...

	usb_con: connector {

		compatible = "usb-c-connector";

		label = "USB-C";

		ports {

			#address-cells = <1>;

			#size-cells = <0>;

			port@0 {

				reg = <0>;

				usb_con_hs: endpoint {

					remote-endpoint = <&max77865_usbc_hs>;

				};

			};

			port@1 {

				reg = <1>;

				usb_con_ss: endpoint {

					remote-endpoint = <&usbdrd_phy_ss>;

				};

			};

			port@2 {

				reg = <2>;

				usb_con_sbu: endpoint {

					remote-endpoint = <&dp_aux>;

				};

			};

		};

	};

};