net/mlx5: fix tunnel flow priority

net/mlx5: fix tunnel flow priority

The PMD manages internally the priority of the flows in addition to the
user configured priority.

So, 2 flows with the same user priority may get different priority.

The method:
As much as the flow is more specific it gets higher priority
(higher means first to be matched).

In addition, When the user creates a RSS flow the PMD splits the flows
according to the flow RSS layers as the HW requests for RSS TIR.
The internal priority for each flow is decided by the flow last layer.
L2, L3 and L4 (L2 low and L4 high).

The tunnel layer was wrongly decided to be L4 all the time, even when
the flow is configured with inner-RSS.

Hence, the first RSS split which takes the tunnel layer priority all the
time will be matched before the more specific splits.

Change the priority of tunnel layer to be L2 when inner-RSS is
configured.

Fixes: d4a405186b73 ("net/mlx5: support tunnel RSS level")
Cc: stable@dpdk.org
Signed-off-by: Matan Azrad <matan@mellanox.com>
Acked-by: Ori Kam <orika@mellanox.com>