mm: memory_hotplug: make offline_pages() static

It has no references outside memory_hotplug.c.

Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 67e941d..f827cf4 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -751,7 +751,7 @@
 	return offlined;
 }
 
-int offline_pages(unsigned long start_pfn,
+static int offline_pages(unsigned long start_pfn,
 		  unsigned long end_pfn, unsigned long timeout)
 {
 	unsigned long pfn, nr_pages, expire;