Generic USB Device Properties

Usually, we only use device tree for hard wired USB device.
The reference binding doc is from:
http://www.devicetree.org/open-firmware/bindings/usb/usb-1_0.ps

Required properties:
- compatible: usbVID,PID. The textual representation of VID, PID shall
  be in lower case hexadecimal with leading zeroes suppressed. The
  other compatible strings from the above standard binding could also
  be used, but a device adhering to this binding may leave out all except
  for usbVID,PID.
- reg: the port number which this device is connecting to, the range
  is 1-255.

Example:

&usb1 {

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

	hub: genesys@1 {
		compatible = "usb5e3,608";
		reg = <1>;
	};
}
