s390/zcrypt: Enable special header file flag for AU CPRP

With the CEX6 there is a new CPRB (subfunction AU) used
to generate protected keys from secure keys. This new
CPRB needs to have the special flag set in the queue
message header struct which is introduced with this fix.

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