netfilter: nf_tables: initialize registers in nft_do_chain()

mainline inclusion
from mainline-v5.18-rc1
commit 4c905f67
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I50WAZ


CVE: CVE-2022-1016

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Initialize registers to avoid stack leak into userspace.

Fixes: 96518518 ("netfilter: add nftables")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

conflict:
	net/netfilter/nf_tables_core.c

Signed-off-by: Lu Wei <luwei32@huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>