luci-app-olsr: re-add missing interface creation

commit c567bfc removed the uci.add() call to create a new interface,
seemingly without considering its side-effects. this lead to trying to
configure a non-existant interface, resulting in an empty settings page.

Signed-off-by: Victoria Grain <victoria+openwrt@gratux.xyz>
(cherry picked from commit d98f03e201)

applications/luci-app-olsr/htdocs/luci-static/resources/view/olsr/frontend/olsrd.js

@@ -483,6 +483,7 @@ return view.extend({
 		};
 
 		ifs.handleAdd = function (ev) {
+			uci.add('olsrd', 'Interface');
 			uci
 				.save()
 				.then(function () {

applications/luci-app-olsr/htdocs/luci-static/resources/view/olsr/frontend/olsrd6.js

@@ -462,6 +462,7 @@ return view.extend({
 		ifs.template = 'cbi/tblsection';
 
 		ifs.handleAdd = function (ev) {
+			uci.add('olsrd6', 'Interface');
 			uci
 				.save()
 				.then(function () {