* Freescale i.MX ci13xxx usb controllers

Required properties:
- compatible: Should be "fsl,imx27-usb"
- reg: Should contain registers location and length
- interrupts: Should contain controller interrupt
- fsl,usbphy: phandle of usb phy that connects to the port

Recommended properies:
- phy_type: the type of the phy connected to the core. Should be one
  of "utmi", "utmi_wide", "ulpi", "serial" or "hsic". Without this
  property the PORTSC register won't be touched
- dr_mode: One of "host", "peripheral" or "otg". Defaults to "otg"

Optional properties:
- fsl,usbmisc: phandler of non-core register device, with one argument
  that indicate usb controller index
- vbus-supply: regulator for vbus
- disable-over-current: disable over current detect
- external-vbus-divider: enables off-chip resistor divider for Vbus
- maximum-speed: limit the maximum connection speed to "full-speed".

Examples:
usb@02184000 { /* USB OTG */
	compatible = "fsl,imx6q-usb", "fsl,imx27-usb";
	reg = <0x02184000 0x200>;
	interrupts = <0 43 0x04>;
	fsl,usbphy = <&usbphy1>;
	fsl,usbmisc = <&usbmisc 0>;
	disable-over-current;
	external-vbus-divider;
	maximum-speed = "full-speed";
};