Merge branch 'nixge-Fixed-link-support'

Moritz Fischer says:

====================
nixge: Fixed-link support

This series adds fixed-link support to nixge.

The first patch corrects the binding to correctly reflect
hardware that does not come with MDIO cores instantiated.

The second patch adds fixed link support to the driver.

The third patch updates the binding document with the now
optional (formerly required) phy-handle property and references
the fixed-link docs.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>