s390/zcrypt: Fix wrong format string in debug feature printout

Fix wrong format string debug feature: %04x was used
to print out a 32 bit value. - changed to %08x.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Ingo Franzki <ifranzki@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>