s390/pkey: harmonize pkey s390 debug feature calls

Cleanup and harmonize the s390 debug feature calls
and defines for the pkey module to be similar to
the debug feature as it is used in the zcrypt device
driver and AP bus.

More or less only renaming but no functional changes.
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>