Introduce a mechanism based on generic ACPI _DSD device properties
definition [1] to get PHYs registered on a MDIO bus and provide them to
be connected to MAC.

[1] http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf

Describe properties "phy-handle" and "phy-mode".
Signed-off-by: NCalvin Johnson <calvin.johnson@oss.nxp.com>
Signed-off-by: NIoana Ciornei <ioana.ciornei@nxp.com>
Acked-by: NRafael J. Wysocki <rafael@kernel.org>
Acked-by: NGrant Likely <grant.likely@arm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>