net/mlx5e: Let mlx5e_get_sw_max_sq_mpw_wqebbs accept mdev

To shorten and simplify code, let mlx5e_get_sw_max_sq_mpw_wqebbs accept
mdev and derive max SQ WQEBBs from it. Also rename the function to a
more generic name mlx5e_get_max_sq_aligned_wqebbs, because the following
patches will use it in non-MPWQE contexts.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>