net/mlx5: Lag, don't use the hardcoded value of the first port

The cited commit didn't change the body of the loop as it should.
It shouldn't be using MLX5_LAG_P1.

Fixes: 7e978e77

 ("net/mlx5: Lag, use actual number of lag ports")
Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Link: https://patch.msgid.link/20240730061638.1831002-5-tariqt@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>