s390/crypto: Add new subfunctions to the cpacf PRNO function.

There is a new TRNG extension in the subcodes for the cpacf
PRNO function. This patch introduces new defines and a new
cpacf_trng inline function to provide these new features for
other kernel code parts.

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