CM layer calls ib_modify_port() regardless of the link layer.

For the Ethernet ports, qkey violation and Port capabilities
are meaningless. Therefore, always return success for ib_modify_port
calls on the Ethernet ports.

Cc: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: NMajd Dibbiny <majd@mellanox.com>
Reviewed-by: NMoni Shoua <monis@mellanox.com>
Signed-off-by: NLeon Romanovsky <leon@kernel.org>
Signed-off-by: NDoug Ledford <dledford@redhat.com>