nfp: flower: utilize the tuple iifidx in offloading ct flows

nfp: flower: utilize the tuple iifidx in offloading ct flows

The device info from which conntrack originates is stored in metadata
field of the ct flow to offload now, driver can utilize it to reduce
the number of offloaded flows.

v2: Drop inline keyword from get_netdev_from_rule() signature.
    The compiler can decide.

Signed-off-by: Yinjun Zhang <yinjun.zhang@corigine.com>
Signed-off-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20220429075124.128589-1-simon.horman@corigine.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>