IB/mlx5: Add additional checks before processing MADs

Check the has_smi bit in vport context and class version of MADs
before allowing MADs processing to take place.
MAD_IFC SMI commands can be executed only if smi bit is set.

Fixes: e126ba97 ('mlx5: Add driver for Mellanox Connect-IB adapters')
Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Parvi Kaustubhi <parvik@mellanox.com>
Reviewed-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>