ofono: removed exit from parse_modem

During development multiple ModemAdded callbacks were seen,
which caused duplicate modems to be created. Since then this
condition has never been seen again, so instead of exiting
we will just print and return. This wont allow duplicate modems
to be created anyways so its much better to do this than fataly
exiting.

plugins/ofono.c

@@ -646,16 +646,10 @@ static void parse_modem(const char *path, struct l_dbus_message_iter *props)
 	l_debug("modem found: %s", path);
 
 	if (l_queue_find(modems, match_modem_by_path, path)) {
-		/*
-		 * TODO: This can be removed once its found why sometimes two
-		 * modem added callbacks happen. It is very infrequent but
-		 * has been seen to happen.
-		 */
+		/* should never happen */
 		l_error("modem %s already found", path);
-#ifdef HAVE_EXECINFO_H
-		__iwd_backtrace_print(2);
-#endif
-		exit(1);
+
+		return;
 	}
 
 	modem = l_new(struct ofono_modem, 1);