ice: low level support for tunnels

Add definition of UDP tunnel dummy packets. Fill destination port value
in filter based on UDP tunnel port. Append tunnel flags to switch filter
definition in case of matching the tunnel.

Both VXLAN and Geneve are UDP tunnels, so only one new header is needed.

Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>