nfp: flower: add ipv4 set ttl and tos offload

Add ipv4 set ttl and tos action offload. Since pedit sets headers per 4
byte word, we need to ensure that setting either version, ihl, protocol,
total length or checksum does not get offloaded.

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