nvme-pci: Fix controller freeze wait disabling

mainline inclusion
from mainline-5.2-rc2
commit e43269e6
category: bugfix
bugzilla: 167363
CVE: NA

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

If a controller disabling didn't start a freeze, don't wait for the
operation to complete.

Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>