Merge branch 'mtk_eth_soc-firmware'

Daniel Golle says:

====================
net: ethernet: mtk_eth_soc: use WO firmware for MT7981

In order to support wireless offloading on MT7981 we need to load the
appropriate firmware. Recognize MT7981 by introducing a new DT compatible
and load mt7981_wo.bin if it is set.

Changes since v1:
 * retain alphabetic order in dt-bindings
====================

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