net/mlx5: E-switch, Prepare code to handle vport enable error

In subsequent patch, esw_enable_vport() could fail and return error.
Prepare code to handle such error.

Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Vu Pham <vuhuong@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>