Merge branch 'mv88e6390-CMODE'

Andrew Lunn says:

====================
Set the CMODE for mv88e6390 ports

The mv88e6390 ports 9 & 10 allow there CMODE to be set. CMODE is part
of what linux defines as phy-mode. Add the needed phy-modes to linux,
and add code which will act upon the phy-mode property to configure
the switch port.

These patches have been posted before as part of a bigger patchset
which has now been broken up. I've added the received reviewed by
tags, and added device tree documentation.
====================

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