Merge mlx5-next patches needed for upcoming mlx5 software steering.

1) Alex adds HW bits and definitions required for SW steering
2) Ariel moves device memory management to mlx5_core (From mlx5_ib)
3) Maor, Cleanups and fixups for eswitch mode and RoCE
4) Mark, Set only stag for match untagged packets
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>