nfp: compile flower vxlan tunnel set actions

Compile set tunnel actions for tc flower. Only support VXLAN and ensure a
tunnel destination port of 4789 is used.

Signed-off-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>