netfilter: connlimit: factor hlist search into new function
netfilter: connlimit: factor hlist search into new function

Simplifies followup patch that introduces separate locks for each of
the hash slots.

Reviewed-by: Jesper Dangaard Brouer <980bdea81946be3dffddbcbbdb1b5761713ff28c@redhat.com>
Signed-off-by: Florian Westphal <cef439e78636cdab99cd2923826c5065a0743e5b@strlen.de>
Signed-off-by: Pablo Neira Ayuso <707d14912bb250caf67dfe0ea4035681fbfc4f56@netfilter.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs