UBI: return on error in rename_volumes()

I noticed this during a code review.  We are checking that the strlen()
of ->name is not less than the ->name_len which the user gave us.  I
believe this bug is harmless but clearly we meant to return here instead
of setting an error code and then not using it.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NArtem Bityutskiy <artem.bityutskiy@linux.intel.com>

drivers/mtd/ubi/cdev.c

@@ -701,7 +701,7 @@ static int rename_volumes(struct ubi_device *ubi,
 		req->ents[i].name[req->ents[i].name_len] = '\0';
 		n = strlen(req->ents[i].name);
 		if (n != req->ents[i].name_len)
-			err = -EINVAL;
+			return -EINVAL;
 	}
 
 	/* Make sure volume IDs and names are unique */