s390/mm: recfactor global pgste updates

Replace the s390 specific page table walker for the pgste updates
with a call to the common code walk_page_range function.
There are now two pte modification functions, one for the reset
of the CMMA state and another one for the initialization of the
storage keys.

Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --cc arch/s390/include/asm/pgalloc.h
Simple merge

diff --cc arch/s390/include/asm/pgtable.h
Simple merge

diff --cc arch/s390/kvm/kvm-s390.c
Simple merge

diff --cc arch/s390/mm/pgtable.c
Simple merge