Add a MV88E6XXX_FLAG_EEE flag to describe switch models featuring Energy
Efficient Ethernet. Use it to conditionally support such access in the
common code.
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>