net/mlx5: Generalize name of UMR alignment definition

Per the device spec, MLX5_UMR_MTT_ALIGNMENT is good not only for UMR MTT
entries, but for all other entries as well, like KLMs and KSMs.

Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>