nvme-multipath: avoid crash on invalid subsystem cntlid enumeration

mainline inclusion
from mainline-v5.2-rc1
commit 8a03b27e
category: bugfix
bugzilla: NA
CVE: NA
Link: https://gitee.com/openeuler/kernel/issues/I4JFBE?from=project-issue



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A process holding an open reference to a removed disk prevents it
from completing deletion, so its name continues to exist. A subsequent
gendisk creation may have the same cntlid which risks collision when
using that for the name. Use the unique ctrl->instance instead.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: chengjike <chengjike.cheng@huawei.com>
Reviewed-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>