netfilter: conntrack: split resolve_clash function

mainline inclusion
from mainline-v5.6-rc3
commit bb89abe5
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I63OS1


CVE: NA

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

Followup patch will need a helper function with the 'clashing entries
refer to the identical tuple in both directions' resolution logic.

This patch will add another resolve_clash helper where loser_ct must
not be added to the dying list because it will be inserted into the
table.

Therefore this also moves the stat counters and dying-list insertion
of the losing ct.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sun Shouxin <sunshouxin@chinatelecom.cn>
Signed-off-by: Xibo.Wang <wangxb12@chinatelecom.cn>

conflict:
	net/netfilter/nf_conntrack_core.c

Signed-off-by: Lu Wei <luwei32@huawei.com>