dt-bindings: net: Broadcom iProc MDIO bus driver device tree binding

* Broadcom iProc MDIO bus controller

Required properties:

- compatible: should be "brcm,iproc-mdio"

- reg: address and length of the register set for the MDIO interface

- #size-cells: must be 1

- #address-cells: must be 0

Child nodes of this MDIO bus controller node are standard Ethernet PHY device

nodes as described in Documentation/devicetree/bindings/net/phy.txt

Example:

mdio@18002000 {

	compatible = "brcm,iproc-mdio";

	reg = <0x18002000 0x8>;

	#size-cells = <1>;

	#address-cells = <0>;

	enet-gphy@0 {

		reg = <0>;

	};

};