[S390] cio: Use isc_{register,unregister}.

Use the new isc registration functions for all places that need
an I/O interruption subclass.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>