nfp: flower: set tunnel ttl value to net default

Firmware requires that the ttl value for an encapsulating ipv4 tunnel
header be included as an action field. Prior to the support of Geneve
tunnel encap (when ttl set was removed completely), ttl value was
extracted from the tunnel key. However, tests have shown that this can
still produce a ttl of 0.

Fix the issue by setting the namespace default value for each new tunnel.
Follow up patch for net-next will do a full route lookup.

Fixes: 3ca3059d ("nfp: flower: compile Geneve encap actions")
Fixes: b27d6a95

 ("nfp: compile flower vxlan tunnel set actions")
Signed-off-by: John Hurley <john.hurley@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>