net/mlx5e: Remove extra layers of defines

Instead of performing redefinition of XFRM core defines to same
values but with MLX5_* prefix, cache the input values as is by making
sure that the proper storage objects are used.

Reviewed-by: Raed Salem <raeds@nvidia.com>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>