[PATCH] mm/memory_hotplug: use helper function zone_end_pfn() to get end_pfn

[Miaohe Lin <linmiaohe@huawei.com>]

Commit 108bcc96ef70 ("mm: add & use zone_end_pfn() and zone_spans_pfn()")
introduced the helper zone_end_pfn() to calculate the zone end pfn.  But
update_pgdat_span() forgot to use it. Use this helper and re-name local
variable zone_end_pfn to end_pfn to fix below compilation error:

mm/memory_hotplug.c: In function ‘update_pgdat_span’:
mm/memory_hotplug.c:448:32: error: called object ‘zone_end_pfn’ is not a
function or function pointer
   unsigned long zone_end_pfn = zone_end_pfn(zone);
                                ^~~~~~~~~~~~
mm/memory_hotplug.c:448:17: note: declared here
   unsigned long zone_end_pfn = zone_end_pfn(zone);
                 ^~~~~~~~~~~~

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/memory_hotplug.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 710e469fb3a1..0483db52b85f 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -493,20 +493,19 @@ static void update_pgdat_span(struct pglist_data *pgdat)
 
 	for (zone = pgdat->node_zones;
 	     zone < pgdat->node_zones + MAX_NR_ZONES; zone++) {
-		unsigned long zone_end_pfn = zone->zone_start_pfn +
-					     zone->spanned_pages;
+		unsigned long end_pfn = zone_end_pfn(zone);
 
 		/* No need to lock the zones, they can't change. */
 		if (!zone->spanned_pages)
 			continue;
 		if (!node_end_pfn) {
 			node_start_pfn = zone->zone_start_pfn;
-			node_end_pfn = zone_end_pfn;
+			node_end_pfn = end_pfn;
 			continue;
 		}
 
-		if (zone_end_pfn > node_end_pfn)
-			node_end_pfn = zone_end_pfn;
+		if (end_pfn > node_end_pfn)
+			node_end_pfn = end_pfn;
 		if (zone->zone_start_pfn < node_start_pfn)
 			node_start_pfn = zone->zone_start_pfn;
 	}
-- 
2.19.1