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>

mm/internal.h

@@ -32,11 +32,6 @@ static inline void set_page_refcounted(struct page *page)
 	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)
 {