ccw_device_halt — halt I/O request processing
target ccw device
interruption parameter; value is only used if no I/O is outstanding, otherwise the intparm associated with the I/O request is returned
ccw_device_halt calls hsch on cdev's subchannel.
0 on success, -ENODEV on device not operational, -EINVAL on invalid device state, -EBUSY on device busy or interrupt pending.
Interrupts disabled, ccw device lock held