net/mlx5: fix matching for UDP tunnels with Verbs

net/mlx5: fix matching for UDP tunnels with Verbs

When creating flow rule with zero specs it will cause
matching all UDP packets like following:
 eth / ipv4 / udp / vxlan / end
Such rule will match all udp packets.

This change the behavior to match the dv flow engine
which will automatically set the match on relative
outer UDP port if the user didn't specify any.

Fixes: 84c406e74524 ("net/mlx5: add flow translate function")
Cc: stable@dpdk.org
Signed-off-by: Raslan Darawsheh <rasland@mellanox.com>
Acked-by: Matan Azrad <matan@mellanox.com>