net/mlx5: Read congestion counters from all ports when lag is active

Read congestion counters from all ports in any lag mode rather than
only in RoCE lag mode (e.g., VF lag).

Signed-off-by: Mark Zhang <markzhang@nvidia.com>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>