net/mlx5: E-switch, Reuse total_vports and avoid duplicate nvports

Total e-switch vports are already stored in mlx5_eswitch total_vports.
Avoid copy of it in nvports and reuse existing total_vports calculation.

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