luci-app-strongswan-swanctl: rename dpddelay to dpd_delay in remote

Rename the 'dpddelay' option to 'dpd_delay' in the uci section type
'remote' to follow the naming convention and improve consistency with
'swanctl.conf' terminology.

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

applications/luci-app-strongswan-swanctl/htdocs/luci-static/resources/view/strongswan-swanctl/swanctl.js

@@ -236,7 +236,7 @@ return view.extend({
 		o.placeholder = '3';
 		o.modalonly = true;
 
-		o = s.taboption('advanced', form.Value, 'dpddelay', _('DPD Delay'),
+		o = s.taboption('advanced', form.Value, 'dpd_delay', _('DPD Delay'),
 			_('Interval to check liveness of a peer'));
 		o.validate = validateTimeFormat;
 		o.placeholder = '30s';