[FIX] website: fix crash when adding item to top menu

In 4d5c3b9f the arguments of the MenuEntryDialog widget were
altered, and one instantiation of this widget was not adapted, resulting
in the last parameter being undefined and causing a crash. This commit
adapts that call.

closes odoo/odoo#40171

Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>