net/sched: act_tunnel_key: Add UDP dst port option

The current tunnel set action supports only IP addresses and key
options. Add UDP dst port option.

Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>