nfp: flower-ct: add offload calls to the nfp

Add the offload parts (ADD_FLOW/DEL_FLOW) calls to add and delete
the flows from the nfp.

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>