Introduce levels of matching on headers of offloaded flows
(none, L2, L3, L4) that follow the inline mode levels.

This is pre-step for us to offload flows without any
matches on headers.
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>