net/mlx5e: SHAMPO, clean MLX5E_MAX_KLM_PER_WQE macro

This commit reduces unused variable from MLX5E_MAX_KLM_PER_WQE macro that
introduced by commit d7b896ac ("net/mlx5e: Add support to klm_umr_wqe").

Signed-off-by: Ben Ben-Ishay <benishay@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>