ST STiH407 USB PHY controller

This file documents the dt bindings for the usb picoPHY driver which is the PHY for both USB2 and USB3
host controllers (when controlling usb2/1.1 devices) available on STiH407 SoC family from STMicroelectronics.

Required properties:
- compatible		: should be "st,stih407-usb2-phy"
- reg			: contain the offset and length of the system configuration registers
			  used as glue logic to control & parameter phy
- reg-names		: the names of the system configuration registers in "reg", should be "param" and "reg"
- st,syscfg		: sysconfig register to manage phy parameter at driver level
- resets		: list of phandle and reset specifier pairs. There should be two entries, one
			  for the whole phy and one for the port
- reset-names		: list of reset signal names. Should be "global" and "port"
See: Documentation/devicetree/bindings/reset/st,sti-powerdown.txt
See: Documentation/devicetree/bindings/reset/reset.txt

Example:

usb2_picophy0: usbpicophy@f8 {
	compatible	= "st,stih407-usb2-phy";
	reg		= <0xf8 0x04>,	/* syscfg 5062 */
			  <0xf4 0x04>;	/* syscfg 5061 */
	reg-names	= "param", "ctrl";
	#phy-cells	= <0>;
	st,syscfg	= <&syscfg_core>;
	resets		= <&softreset STIH407_PICOPHY_SOFTRESET>,
			  <&picophyreset STIH407_PICOPHY0_RESET>;
	reset-names	= "global", "port";
};