start via hotplug only if enabled

To be consistent with other services only start via hotplug if enabled.
Now full functionality of /etc/init.d/ddns enable/disable start/stop

Optimization: Include script only if needed

net/ddns-scripts/files/etc/hotplug.d/iface/25-ddns

@@ -1,9 +1,7 @@
 #!/bin/sh
 
-. /usr/lib/ddns/dynamic_dns_functions.sh
-
 if [ "$ACTION" = "ifup" ]; then
-	start_daemon_for_all_ddns_sections "$INTERFACE"
+	. /usr/lib/ddns/dynamic_dns_functions.sh
+	/etc/init.d/ddns enabled && start_daemon_for_all_ddns_sections "$INTERFACE"
 fi
 
-