nvme: fix controller instance leak

mainline inclusion
from mainline-v5.9
commit 192f6c29
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5986O


CVE: NA

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If the driver has to unbind from the controller for an early failure
before the subsystem has been set up, there won't be a subsystem holding
the controller's instance, so the controller needs to free its own
instance in this case.

Fixes: 733e4b69 ("nvme: Assign subsys instance from first ctrl")
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Xibo.Wang <wangxb12@chinatelecom.cn>