Merge branch 'net-phy-add-and-use-further-MMD-accessors'

Heiner Kallweit says:

====================
net: phy: add and use further MMD accessors

Add MMD accessors for modifying MMD registers and clearing / setting
bits in MMD registers. Use these accessors in PHY drivers and phylib.

v2:
- fix SoB in patch 2
====================

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