s390/cio: unregister device when the only path is gone

stable inclusion
from stable-v5.10.186
commit 97b6c4c1d1a8483818e5fd46112409cead4ac0f7
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8J4KH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=97b6c4c1d1a8483818e5fd46112409cead4ac0f7



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[ Upstream commit 89c0c62e ]

Currently, if the device is offline and all the channel paths are
either configured or varied offline, the associated subchannel gets
unregistered. Don't unregister the subchannel, instead unregister
offline device.

Signed-off-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>