[FIX] website: seo - fix translation for seo modal

Lang / Context is implicitely added in the query using this._rpc

Before this commit if you set the title 'Title 1' for your website in the main
langage and after edit the title as "Title 2" in another language, it was the
main title that was replaced instead of the translation.

Now we use this._rpc that bind automatically the context and so the current lang
that we are editing.

addons/website/static/src/js/menu/seo.js

@@ -764,7 +764,7 @@ var SeoConfigurator = Dialog.extend({
         if (!obj) {
             return $.Deferred().reject();
         } else {
-            return rpc.query({
+            return this._rpc({
                 model: obj.model,
                 method: 'write',
                 args: [[obj.id], data],