mm/vmstat.c: walk the zone in pageblock_nr_pages steps

when walking the zone, we can happens to the holes. we should not
align MAX_ORDER_NR_PAGES, so it can skip the normal memory.

In addition, pagetypeinfo_showmixedcount_print reflect fragmentization.
we hope to get more accurate data. therefore, I decide to fix it.

Link: http://lkml.kernel.org/r/1469502526-24486-2-git-send-email-zhongjiang@huawei.com
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: xiongzhongjiang

mm/page_owner.c

@@ -261,7 +261,7 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,
 	 */
 	for (; pfn < end_pfn; ) {
 		if (!pfn_valid(pfn)) {
-			pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
+			pfn = ALIGN(pfn + 1, pageblock_nr_pages);
 			continue;
 		}