[S390] cio: fix memleak in resume path

If a ccwdevice is lost during hibernation and a different
ccwdevice is attached to the same subchannel, we will
deregister the old ccw device and register the new one.

Since deregistration is not allowed in this context, we
handle this action later. However, some parts of the
registration process for the new device were started anyway,
so that the old device structure is no longer accessible.

Fix this by deferring both actions to the afterwards
scheduled subchannel event.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>