nfp: offload vxlan IPv4 endpoints of flower rules

Maintain a list of IPv4 addresses used as the tunnel destination IP match
fields in currently active flower rules. Offload the entire list of
NFP_FL_IPV4_ADDRS_MAX (even if some are unused) when new IPs are added or
removed. The NFP should only be aware of tunnel end points that are
currently used by rules on the device

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