s390/zcrypt: add missing memory clobber to ap_qci inline assembly

The ap_qci() inline assembly writes to memory (*config) but misses to
tell the compiler about it. Add the missing memory clobber to fix
this.

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