netfilter: nft_set_hash: GC reaps elements with conncount for dynamic sets only

[ Upstream commit 9d74da11 ]

conncount has its own GC handler which determines when to reap stale
elements, this is convenient for dynamic sets. However, this also reaps
non-dynamic sets with static configurations coming from control plane.
Always run connlimit gc handler but honor feedback to reap element if
this set is dynamic.

Fixes: 290180e2 ("netfilter: nf_tables: add connlimit support")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>