* USB2 ChipIdea USB controller for ci13xxx

Required properties:
- compatible: should be one of:
	"fsl,imx27-usb"
	"lsi,zevio-usb"
	"qcom,ci-hdrc"
	"chipidea,usb2"
	"xlnx,zynq-usb-2.20a"
- reg: base address and length of the registers
- interrupts: interrupt for the USB controller

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"

Deprecated properties:
- usb-phy:      phandle for the PHY device. Use "phys" instead.
- fsl,usbphy: phandle of usb phy that connects to the port. Use "phys" instead.

Optional properties:
- clocks: reference to the USB clock
- phys: reference to the USB PHY
- phy-names: should be "usb-phy"
- vbus-supply: reference to the VBUS regulator
- maximum-speed: limit the maximum connection speed to "full-speed".
- tpl-support: TPL (Targeted Peripheral List) feature for targeted hosts
- itc-setting: interrupt threshold control register control, the setting
  should be aligned with ITC bits at register USBCMD.
- ahb-burst-config: it is vendor dependent, the required value should be
  aligned with AHBBRST at SBUSCFG, the range is from 0x0 to 0x7. This
  property is used to change AHB burst configuration, check the chipidea
  spec for meaning of each value. If this property is not existed, it
  will use the reset value.
- tx-burst-size-dword: it is vendor dependent, the tx burst size in dword
  (4 bytes), This register represents the maximum length of a the burst
  in 32-bit words while moving data from system memory to the USB
  bus, the value of this property will only take effect if property
  "ahb-burst-config" is set to 0, if this property is missing the reset
  default of the hardware implementation will be used.
- rx-burst-size-dword: it is vendor dependent, the rx burst size in dword
  (4 bytes), This register represents the maximum length of a the burst
  in 32-bit words while moving data from the USB bus to system memory,
  the value of this property will only take effect if property
  "ahb-burst-config" is set to 0, if this property is missing the reset
  default of the hardware implementation will be used.
- extcon: phandles to external connector devices. First phandle should point to
  external connector, which provide "USB" cable events, the second should point
  to external connector device, which provide "USB-HOST" cable events. If one
  of the external connector devices is not required, empty <0> phandle should
  be specified.
- phy-clkgate-delay-us: the delay time (us) between putting the PHY into
  low power mode and gating the PHY clock.

i.mx specific properties
- fsl,usbmisc: phandler of non-core register device, with one
  argument that indicate usb controller index
- disable-over-current: disable over current detect
- external-vbus-divider: enables off-chip resistor divider for Vbus

Example:

	usb@f7ed0000 {
		compatible = "chipidea,usb2";
		reg = <0xf7ed0000 0x10000>;
		interrupts = <GIC_SPI 11 IRQ_TYPE_LEVEL_HIGH>;
		clocks = <&chip CLKID_USB0>;
		phys = <&usb_phy0>;
		phy-names = "usb-phy";
		vbus-supply = <&reg_usb0_vbus>;
		gadget-itc-setting = <0x4>; /* 4 micro-frames */
		 /* Incremental burst of unspecified length */
		ahb-burst-config = <0x0>;
		tx-burst-size-dword = <0x10>; /* 64 bytes */
		rx-burst-size-dword = <0x10>;
		extcon = <0>, <&usb_id>;
		phy-clkgate-delay-us = <400>;
	};