net/sched: act_ct: Make tcf_ct_flow_table_restore_skb inline

Currently, tcf_ct_flow_table_restore_skb is exported by act_ct
module, therefore modules using it will have hard-dependency
on act_ct and will require loading it all the time.

This can lead to an unnecessary overhead on systems that do not
use hardware connection tracking action (ct_metadata action) in
the first place.

To relax the hard-dependency between the modules, we unexport this
function and make it a static inline one.

Fixes: 30b0cf90

 ("net/sched: act_ct: Support restoring conntrack info on skbs")
Signed-off-by: Alaa Hleihel <alaa@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>