USB GPIO Based Connection Detection

This is typically used to switch dual role mode from the USB ID pin connected
to an input GPIO, and also used to enable/disable device mode from the USB
Vbus pin connected to an input GPIO.

Required properties:
- compatible : should include "gpio-usb-b-connector" and "usb-b-connector".
- id-gpios, vbus-gpios : input gpios, either one of them must be present,
	and both can be present as well.
	see connector/usb-connector.txt

Optional properties:
- vbus-supply : can be present if needed when supports dual role mode.
	see connector/usb-connector.txt

- Sub-nodes:
	- port : can be present.
		see graph.txt

Example:

&mtu3 {
	connector {
		compatible = "gpio-usb-b-connector", "usb-b-connector";
		type = "micro";
		id-gpios = <&pio 12 GPIO_ACTIVE_HIGH>;
		vbus-supply = <&usb_p0_vbus>;
	};
};
