* Renesas R-Car generation 2 USB PHY

This file provides information on what the device node for the R-Car generation
2 USB PHY contains.

Required properties:
- compatible: "renesas,usb-phy-r8a7790" if the device is a part of R8A7790 SoC.
	      "renesas,usb-phy-r8a7791" if the device is a part of R8A7791 SoC.
	      "renesas,usb-phy-r8a7794" if the device is a part of R8A7794 SoC.
- reg: offset and length of the register block.
- #address-cells: number of address cells for the USB channel subnodes, must
		  be <1>.
- #size-cells: number of size cells for the USB channel subnodes, must be <0>.
- clocks: clock phandle and specifier pair.
- clock-names: string, clock input name, must be "usbhs".

The USB PHY device tree node should have the subnodes corresponding to the USB
channels. These subnodes must contain the following properties:
- reg: the USB controller selector; see the table below for the values.
- #phy-cells: see phy-bindings.txt in the same directory, must be <1>.

The phandle's argument in the PHY specifier is the USB controller selector for
the USB channel; see the selector meanings below:

+-----------+---------------+---------------+
|\ Selector |               |               |
+ --------- +       0       |       1       |
| Channel  \|               |               |
+-----------+---------------+---------------+
| 0         | PCI EHCI/OHCI | HS-USB        |
| 2         | PCI EHCI/OHCI | xHCI          |
+-----------+---------------+---------------+

Example (Lager board):

	usb-phy@e6590100 {
		compatible = "renesas,usb-phy-r8a7790";
		reg = <0 0xe6590100 0 0x100>;
		#address-cells = <1>;
		#size-cells = <0>;
		clocks = <&mstp7_clks R8A7790_CLK_HSUSB>;
		clock-names = "usbhs";

		usb-channel@0 {
			reg = <0>;
			#phy-cells = <1>;
		};
		usb-channel@2 {
			reg = <2>;
			#phy-cells = <1>;
		};
	};
