net: emaclite: adding MDIO and phy lib support

These changes add MDIO and phy lib support to the driver as the
IP core now supports the MDIO bus.

The MDIO bus and phy are added as a child to the emaclite in the device
tree as illustrated below.

mdio {
	#address-cells = <1>;
	#size-cells = <0>;
	phy0: phy@7 {
		compatible = "marvell,88e1111";
		reg = <7>;
	} ;
}

Signed-off-by: Sadanand Mutyala <Sadanand.Mutyala@xilinx.com>
Signed-off-by: John Linn <john.linn@xilinx.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>