* Freescale MXS USB Phy Device

Required properties:
- compatible: should contain:
	* "fsl,imx23-usbphy" for imx23 and imx28
	* "fsl,imx6q-usbphy" for imx6dq and imx6dl
	* "fsl,imx6sl-usbphy" for imx6sl
	* "fsl,vf610-usbphy" for Vybrid vf610
	* "fsl,imx6sx-usbphy" for imx6sx
	* "fsl,imx6ul-usbphy" for imx6ul
  "fsl,imx23-usbphy" is still a fallback for other strings
- reg: Should contain registers location and length
- interrupts: Should contain phy interrupt
- fsl,anatop: phandle for anatop register, it is only for imx6 SoC series

Optional properties:
- tx-d-cal: Try to adjust this value to improve signal quality, and pass
  USB Certification, the value is from 0x0 to 0xf, and the register offset
  is 0x10 (USBPHY_TX).

Example:
usbphy1: usbphy@020c9000 {
	compatible = "fsl,imx6q-usbphy", "fsl,imx23-usbphy";
	reg = <0x020c9000 0x1000>;
	interrupts = <0 44 0x04>;
	fsl,anatop = <&anatop>;
	tx-d-cal = <0x5>;
};