UBI: fix return error code

We are checking dfs_rootdir for error value or NULL. But in the
conditional ternary operator we returned -ENODEV if dfs_rootdir contains
an error value and returned PTR_ERR(dfs_rootdir) if dfs_rootdir is NULL.
So in the case of dfs_rootdir being NULL we actually assigned 0 to err
and returned it to the caller implying a success.
Lets return -ENODEV when dfs_rootdir is NULL else return
PTR_ERR(dfs_rootdir).
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Richard Weinberger <richard@nod.at>

drivers/mtd/ubi/debug.c

@@ -236,7 +236,7 @@ int ubi_debugfs_init(void)
 
 	dfs_rootdir = debugfs_create_dir("ubi", NULL);
 	if (IS_ERR_OR_NULL(dfs_rootdir)) {
-		int err = dfs_rootdir ? -ENODEV : PTR_ERR(dfs_rootdir);
+		int err = dfs_rootdir ? PTR_ERR(dfs_rootdir) : -ENODEV;
 
 		pr_err("UBI error: cannot create \"ubi\" debugfs directory, error %d\n",
 		       err);