* Marvell MDIO Ethernet Controller interface

The Ethernet controllers of the Marvel Kirkwood, Dove, Orion5x,
MV78xx0, Armada 370 and Armada XP have an identical unit that provides
an interface with the MDIO bus. This driver handles this MDIO
interface.

Required properties:
- compatible: "marvell,orion-mdio"
- reg: address and length of the SMI register

Optional properties:
- interrupts: interrupt line number for the SMI error/done interrupt
- clocks: Phandle to the clock control device and gate bit

The child nodes of the MDIO driver are the individual PHY devices
connected to this MDIO bus. They must have a "reg" property given the
PHY address on the MDIO bus.

Example at the SoC level:

mdio {
	#address-cells = <1>;
	#size-cells = <0>;
	compatible = "marvell,orion-mdio";
	reg = <0xd0072004 0x4>;
};

And at the board level:

mdio {
	phy0: ethernet-phy@0 {
		reg = <0>;
	};

	phy1: ethernet-phy@1 {
		reg = <1>;
	};
}