s390/ctcm: don't use intparm for channel IO

ctcm passes an intparm when calling ccw_device_*(), even though
ctcm_irq_handler() later makes no use of this.

To reduce the confusion, consistently pass 0 as intparm instead.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>