IB/mlx5: Enforce DEVX privilege by firmware

Enforce DEVX privilege by firmware, this enables future device
functionality without the need to make driver changes unless a new
privilege type will be introduced.

Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Reviewed-by: Artemy Kovalyov <artemyko@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>