net/mlx5: E-Switch, Protect changing mode while adding rules

We re-use the native NIC port net device instance for the Uplink
representor, a driver currently cannot unbind TC setup callback
actively, hence protect changing E-Switch mode while adding rules.

Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>