nfp: offload flow steering to the nfp

This is the second part to implement flow steering. Mailbox is used
for the communication between driver and HW.

Signed-off-by: Yinjun Zhang <yinjun.zhang@corigine.com>
Signed-off-by: Louis Peens <louis.peens@corigine.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20231117071114.10667-3-louis.peens@corigine.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>