nfp: flower-ct: implement code to save merge of tc and nft flows

Add in the code to merge the tc_merge objects with the flows
received from nft. At the moment flows are just merged blindly
as the validity check functions are stubbed out, this will
be populated in follow-up patches.

Signed-off-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: Yinjun Zhang <yinjun.zhang@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>