s390/zcrypt: externalize AP queue interrupt control

KVM has a need to control the interrupts on real and virtualized
AP queue devices. This fix provides a new function to control
the interrupt facilities of an AP queue device.

Signed-off-by: Harald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>