[S390] ap: skip device registration on type probe failure

The registration of an ap device will be skipped, if the device type
probing fails.
Add names of current crypto adapters to the Kconfig help.

Signed-off-by: Holger Dengler <hd@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>