PHY nodes

Required properties:

 - device_type : Should be "ethernet-phy"
 - interrupts : <a b> where a is the interrupt number and b is a
   field that represents an encoding of the sense and level
   information for the interrupt.  This should be encoded based on
   the information in section 2) depending on the type of interrupt
   controller you have.
 - interrupt-parent : the phandle for the interrupt controller that
   services interrupts for this device.
 - reg : The ID number for the phy, usually a small integer
 - linux,phandle :  phandle for this node; likely referenced by an
   ethernet controller node.

Example:

ethernet-phy@0 {
	linux,phandle = <2452000>
	interrupt-parent = <40000>;
	interrupts = <35 1>;
	reg = <0>;
	device_type = "ethernet-phy";
};
