mm: use populated_zone() instead of if(zone->present_pages)

Use "if (zone->present_pages)" instead of "if (zone->present_pages)".
Simplify the code, no functional change.
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -4266,7 +4266,7 @@ static __meminit void zone_pcp_init(struct zone *zone)
 	 */
 	zone->pageset = &boot_pageset;
 
-	if (zone->present_pages)
+	if (populated_zone(zone))
 		printk(KERN_DEBUG "  %s zone: %lu pages, LIFO batch:%u\n",
 			zone->name, zone->present_pages,
 					 zone_batchsize(zone));
@@ -5160,7 +5160,7 @@ static void check_for_memory(pg_data_t *pgdat, int nid)
 
 	for (zone_type = 0; zone_type <= ZONE_MOVABLE - 1; zone_type++) {
 		struct zone *zone = &pgdat->node_zones[zone_type];
-		if (zone->present_pages) {
+		if (populated_zone(zone)) {
 			node_set_state(nid, N_HIGH_MEMORY);
 			if (N_NORMAL_MEMORY != N_HIGH_MEMORY &&
 			    zone_type <= ZONE_NORMAL)