net/mlx5e: Get the required HW match level while parsing TC flow matches

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>