net/sched: act_ct: fix err check for nf_conntrack_confirm

stable inclusion
from stable-5.10.53
commit c3bc9ce7d400718b8341aab0f4fe86d2cf6a3715
bugzilla: 175574 https://gitee.com/openeuler/kernel/issues/I4DTUX

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c3bc9ce7d400718b8341aab0f4fe86d2cf6a3715



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commit 8955b90c upstream.

The confirm operation should be checked. If there are any failed,
the packet should be dropped like in ovs and netfilter.

Fixes: b57dc7c1 ("net/sched: Introduce action ct")
Signed-off-by: wenxu <wenxu@ucloud.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>