nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed

mainline inclusion
from mainline-v5.19-rc1
commit 2895f183
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5H32C
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2895f1831e911ca87d4efdf43e35eb72a0c7e66e



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

Otherwise io will hung because request will only be completed if the
cmd has the flag 'NBD_CMD_INFLIGHT'.

Fixes: 07175cb1 ("nbd: make sure request completion won't concurrent")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20220521073749.3146892-4-yukuai3@huawei.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>