net/mlx5: Remove redundant cmdif revision check

mlx5 is checking the cmdif revision twice, for no reason.
Remove the latter check.

Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>