Intel/Lantiq GPHY firmware loader

This file documents the dt bindings for the Intel/Lantiq GPHY firmware
loader, currently used in xrx500 and prx300 platform.

Required properties:
- compatible	: "lantiq,phy-xrx500" for xrx500 platform
		  "intel,phy-prx300" for prx300 platform
- firmware	: firmware file name
- reg		: register address
- resets	: list of phandle and reset specifier pairs.
- reset-names	: list of reset signal names.
  Reset and reset names are platform specific

For prx300 platform:
- intel,syscon	: phandle to syscon chiptop
- intel,cgu-syscon	: phandle to syscon cgu

Example:

phy_fw: phy-xrx500@3c00 {
	compatible = "lantiq,phy-xrx500";
	reg = <0x3c00 0x400>;
	firmware = "ltq_fw_PHY11G_IP_xRx5xx_A21.bin";
	resets = <&rcu0 0x10 29>, <&rcu0 0x10 28>,
		 <&rcu0 0x10 26>, <&rcu0 0x10 25>,
		 <&rcu0 0x10 31>;
	reset-names = "phy0", "phy1", "phy2", "phy3", "phy4";
};

phy_fw: phy-prx300@210100 {
	compatible = "intel,phy-prx300";
	reg = <0x210100 0x10>;
	firmware = "ltq_fw_PHY31G_IP_prx3xx_A11.bin";
	resets = <&rcu0 0x10 29>, <&rcu0 0x48 28>,
		 <&rcu0 0x48 27>;
	reset-names = "gphy", "gphy_cdb", "gphy_pwr_down";
	intel,syscon = <&sysconf>; /* chiptop */
	intel,cgu-syscon = <&cgu0>;
};