Up until now the device always reported autonegotiation to be off
although it was on by default.

Allow the user to disable / enable autonegotiation and report its status
correctly.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>