s390/cio: Purge based on the cdev's online status

s390/cio: Purge based on the cdev's online status

Ensure that all devices currently offline are purged correctly.

Previously, purging logic relied on the internal FSM state to
determine whether a device was offline. However, devices with a
target state of offline could be skipped if CIO internal
processing was still ongoing during the purge operation.

Update the purge decision logic to rely on the online variable
in the cdev structure instead of the internal FSM state,
providing a more reliable indication of actual device
availability.

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>