x86, mm: s/PAGES_PER_ELEMENT/PAGES_PER_SECTION/

DISCONTIGMEM on x86-32 implements pfn -> nid mapping similarly to
SPARSEMEM; however, it calls each mapping unit ELEMENT instead of
SECTION.  This patch renames it to SECTION so that PAGES_PER_SECTION
is valid for both DISCONTIGMEM and SPARSEMEM.  This will be used by
the next patch to implement mapping granularity check.

This patch is trivial constant rename.

Signed-off-by: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/20110712074422.GA2872@htj.dyndns.org
Cc: Hans Rosenfeld <hans.rosenfeld@amd.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/mm/numa_32.c

@@ -41,7 +41,7 @@
  *     physnode_map[16-31] = 1;
  *     physnode_map[32- ] = -1;
  */
-s8 physnode_map[MAX_ELEMENTS] __read_mostly = { [0 ... (MAX_ELEMENTS - 1)] = -1};
+s8 physnode_map[MAX_SECTIONS] __read_mostly = { [0 ... (MAX_SECTIONS - 1)] = -1};
 EXPORT_SYMBOL(physnode_map);
 
 void memory_present(int nid, unsigned long start, unsigned long end)
@@ -52,8 +52,8 @@ void memory_present(int nid, unsigned long start, unsigned long end)
 			nid, start, end);
 	printk(KERN_DEBUG "  Setting physnode_map array to node %d for pfns:\n", nid);
 	printk(KERN_DEBUG "  ");
-	for (pfn = start; pfn < end; pfn += PAGES_PER_ELEMENT) {
-		physnode_map[pfn / PAGES_PER_ELEMENT] = nid;
+	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
+		physnode_map[pfn / PAGES_PER_SECTION] = nid;
 		printk(KERN_CONT "%lx ", pfn);
 	}
 	printk(KERN_CONT "\n");