qed: Add Light L2 support

Other protocols beside the networking driver need the ability
of passing some L2 traffic, usually [although not limited] for the
purpose of some management traffic.

Signed-off-by: Yuval Mintz <Yuval.Mintz@caviumnetworks.com>
Signed-off-by: Ram Amrani <Ram.Amrani@caviumnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>