net/mlx5: DR, Adjust structure member to reduce memory hole

Accord to profiling, mlx5dr_ste/mlx5dr_icm_chunk are the two
hot structures. Their memory layout can be optimized by
adjusting member sequences.

Struct mlx5dr_ste size changes from 64 bytes to 56 bytes.

In the upcoming commits, struct mlx5dr_icm_chunk memory layout
will change automatically after removing some members.
Keep it untouched here.

Signed-off-by: Rongwei Liu <rongweil@nvidia.com>
Reviewed-by: Shun Hao <shunh@nvidia.com>
Reviewed-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>