net/mlx5: fix flow tunnel handling

net/mlx5: fix flow tunnel handling

Both rte_flow and mlx5_flow redundantly have item flags. And it is not
properly set in the code. This causes wrong tunnel flag handling. A
rte_flow can have multiple expanded device flows if the flow has an RSS
action. Therefore, mlx5_flow should have the layers field.

Fixes: c4d9b9f7f382 ("net/mlx5: add Direct Verbs final functions")
Fixes: fc2c498ccb94 ("net/mlx5: add Direct Verbs translate items")
Fixes: 3d69434113d1 ("net/mlx5: add Direct Verbs validation function")
Fixes: 84c406e74524 ("net/mlx5: add flow translate function")
Fixes: 4e05a229c5da ("net/mlx5: add flow prepare function")
Fixes: 23c1d42c7138 ("net/mlx5: split flow validation to dedicated function")

Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>