IB/mlx5: Avoid dealing with vport representors if not being e-switch manager

In smartnic env, the host (PF) driver might not be an e-switch
manager, hence the switchdev mode representors are running on
the embedded cpu (EC) and not at the host.

As such, we should avoid dealing with vport representors if
not being esw manager.

Fixes: b5ca15ad ('IB/mlx5: Add proper representors support')
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>