* Allwinner A10 MDIO Ethernet Controller interface

Required properties:
- compatible: should be "allwinner,sun4i-mdio".
- reg: address and length of the register set for the device.

Optional properties:
- phy-supply: phandle to a regulator if the PHY needs one

Example at the SoC level:
mdio@01c0b080 {
        compatible = "allwinner,sun4i-mdio";
        reg = <0x01c0b080 0x14>;
        #address-cells = <1>;
        #size-cells = <0>;
};

And at the board level:

mdio@01c0b080 {
        phy-supply = <&reg_emac_3v3>;

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