include/linux/mm.h: remove unneeded ifdef

The check code for CONFIG_SWAP is redundant, because there is a
non-CONFIG_SWAP version for PageSwapCache() which just returns 0.

Signed-off-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1202cd3..52b2645 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -643,12 +643,9 @@
 	struct address_space *mapping = page->mapping;
 
 	VM_BUG_ON(PageSlab(page));
-#ifdef CONFIG_SWAP
 	if (unlikely(PageSwapCache(page)))
 		mapping = &swapper_space;
-	else
-#endif
-	if (unlikely((unsigned long)mapping & PAGE_MAPPING_ANON))
+	else if (unlikely((unsigned long)mapping & PAGE_MAPPING_ANON))
 		mapping = NULL;
 	return mapping;
 }