f2fs: alloc_page() doesn't return an ERR_PTR

alloc_page() returns a NULL on failure, it never returns an ERR_PTR.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 1c21344..818ff36 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1517,8 +1517,8 @@
 
 	/* alloc temporal page for read node */
 	page = alloc_page(GFP_NOFS | __GFP_ZERO);
-	if (IS_ERR(page))
-		return PTR_ERR(page);
+	if (!page)
+		return -ENOMEM;
 	lock_page(page);
 
 	/* scan the node segment */