qede: introduce support for FEC control

Add Ethtool callbacks for querying and setting FEC parameters if it's
supported by the underlying qed module and MFW version running on the
device.

Signed-off-by: Alexander Lobakin <alobakin@marvell.com>
Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>