s390/mm: allow order 10 allocations

Get rid of FORCE_MAX_ZONEORDER which limited allocations to order 8 (= 1MB)
and use the default, which allows for order 10 (= 4MB) allocations.

Given that s390 allows less than the default this caused some memory
allocation problems more or less unique to s390 from time to time.

Note: this was originally introduced with commit 684de39b ("[S390]
Fix IPL from NSS.") in order to support Named Saved Segments, which
could start/end at an arbitrary 1 megabyte boundary and also before
support for sparsemem vmemmmap was enabled.

Since NSS support is gone, but sparsemem vmemmap support is available
this limitation can go away.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/Kconfig

@@ -625,10 +625,6 @@ config ARCH_ENABLE_MEMORY_HOTREMOVE
 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 	def_bool y
 
-config FORCE_MAX_ZONEORDER
-	int
-	default "9"
-
 config MAX_PHYSMEM_BITS
 	int "Maximum size of supported physical memory in bits (42-53)"
 	range 42 53