Revert "netfilter: x_tables: Update remaining dereference to RCU"

stable inclusion
from linux-4.19.184
commit 74bc0e5132581974f4f2b559540a59665a7cf96a

--------------------------------

[ Upstream commit abe7034b ]

This reverts commit 443d6e86.

This (and the following) patch basically re-implemented the RCU
mechanisms of patch 78454473. That patch was replaced because of the
performance problems that it created when replacing tables. Now, we have
the same issue: the call to synchronize_rcu() makes replacing tables
slower by as much as an order of magnitude.

Revert these patches and fix the issue in a different way.

Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>