Revert "net/mlx5: Block entering switchdev mode with ns inconsistency"

This reverts commit 662404b2.
The revert is required due to the suspicion it is not good for anything
and cause crash.

Fixes: 662404b2 ("net/mlx5e: Block entering switchdev mode with ns inconsistency")
Signed-off-by: Gavin Li <gavinl@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>