s390/pkey: introduce reverse x-mas trees

This patch introduces reverse x-mas trees for all
local variables on all the functions in pkey.

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