[S390] cio: consolidate subchannel intparm reset

Ensure that the hardware interruption parameter for a subchannel is
reset when the associated subchannel data structure is freed.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>