s390/zcrypt: improve device probing for zcrypt adapter cards

Improve device probing process for zcrypt adapters to
transmit service request during registration process.

Signed-off-by: Ingo Tuchscherer <ingo.tuchscherer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>