nfp: flower: rename tunnel related functions in action offload

Previously tunnel related functions in action offload only applied
to UDP tunnels. Rename these functions in preparation for new
tunnel types.

Signed-off-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>