nfp: flower-ct: add flow_pay to the offload table

Compile the offload flow metadata and add flow_pay to the offload
table. Also add in the delete paths. This does not include actual
offloading to the card yet, this will follow soon.

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>