mm: remove unused __put_page()

This function is nowhere used, and it has a confusing name with put_page
in mm/swap.c.  So better to remove it.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/internal.h b/mm/internal.h
index 8562de0..4390ac6 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -32,11 +32,6 @@
 	set_page_count(page, 1);
 }
 
-static inline void __put_page(struct page *page)
-{
-	atomic_dec(&page->_count);
-}
-
 static inline void __get_page_tail_foll(struct page *page,
 					bool get_page_head)
 {