IA64: SPARSEMEM_VMEMMAP 16K page size support

Equip IA64 sparsemem with a virtual memmap.  This is similar to the existing
CONFIG_VIRTUAL_MEM_MAP functionality for DISCONTIGMEM.  It uses a PAGE_SIZE
mapping.

This is provided as a minimally intrusive solution.  We split the 128TB
VMALLOC area into two 64TB areas and use one for the virtual memmap.

This should replace CONFIG_VIRTUAL_MEM_MAP long term.

[apw@shadowen.org: convert to new helper based initialisation]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 2e6310b..802b082 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -348,6 +348,7 @@
 config ARCH_SPARSEMEM_ENABLE
 	def_bool y
 	depends on ARCH_DISCONTIGMEM_ENABLE
+	select SPARSEMEM_VMEMMAP_ENABLE
 
 config ARCH_DISCONTIGMEM_DEFAULT
 	def_bool y if (IA64_SGI_SN2 || IA64_GENERIC || IA64_HP_ZX1 || IA64_HP_ZX1_SWIOTLB)