s390/zcrypt: get rid of variable length arrays

The variable length arrays used to specify clobbered memory within
ap_nqap and ap_dqap would only work if the length would be known at
compile time.
This is not the case for both usages. Therefore simply use a full
memory clobber and get rid of the old construct.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>