Freescale QUICC Engine USB Controller

Required properties:
- compatible : should be "fsl,<chip>-qe-usb", "fsl,mpc8323-qe-usb".
- reg : the first two cells should contain usb registers location and
  length, the next two two cells should contain PRAM location and
  length.
- interrupts : should contain USB interrupt.
- interrupt-parent : interrupt source phandle.
- fsl,fullspeed-clock : specifies the full speed USB clock source:
  "none": clock source is disabled
  "brg1" through "brg16": clock source is BRG1-BRG16, respectively
  "clk1" through "clk24": clock source is CLK1-CLK24, respectively
- fsl,lowspeed-clock : specifies the low speed USB clock source:
  "none": clock source is disabled
  "brg1" through "brg16": clock source is BRG1-BRG16, respectively
  "clk1" through "clk24": clock source is CLK1-CLK24, respectively
- hub-power-budget : USB power budget for the root hub, in mA.
- gpios : should specify GPIOs in this order: USBOE, USBTP, USBTN, USBRP,
  USBRN, SPEED (optional), and POWER (optional).

Example:

usb@6c0 {
	compatible = "fsl,mpc8360-qe-usb", "fsl,mpc8323-qe-usb";
	reg = <0x6c0 0x40 0x8b00 0x100>;
	interrupts = <11>;
	interrupt-parent = <&qeic>;
	fsl,fullspeed-clock = "clk21";
	gpios = <&qe_pio_b  2 0 /* USBOE */
		 &qe_pio_b  3 0 /* USBTP */
		 &qe_pio_b  8 0 /* USBTN */
		 &qe_pio_b  9 0 /* USBRP */
		 &qe_pio_b 11 0 /* USBRN */
		 &qe_pio_e 20 0 /* SPEED */
		 &qe_pio_e 21 0 /* POWER */>;
};
