command: return COMMAND_RETURN_OK in handle_addid()

At the last line of handle_addid(), the playlist_result value has
already been evaluated.  Don't return this variable, it's the wrong
type.

src/command.c

@@ -618,7 +618,7 @@ handle_addid(struct client *client, int argc, char *argv[])
 	}
 
 	client_printf(client, "Id: %u\n", added_id);
-	return result;
+	return COMMAND_RETURN_OK;
 }
 
 static enum command_return