net/mwan3: add init script to enable/disable mwan3 globally

Adding a init script to "/etc/init.d/" introduce the possibility to
enable/disable mwan3 globally.

Signed-off-by: Florian Eckert <fe@dev.tdt.de>

net/mwan3/files/etc/hotplug.d/iface/14-mwan3

@@ -12,6 +12,9 @@ if [ "$ACTION" = "ifup" ]; then
 fi
 
 config_load mwan3
+config_get_bool enabled globals 'enabled' '0'
+[ ${enabled} -gt 0 ] || exit 0
+
 config_get local_source globals local_source 'none'
 [ "${local_source}" = "none" ] && {
 	exit 0