(ui) select highest visible option in hook_ipv4v6

(cherry picked from commit ebe341ec)

src/www/javascript/opnsense_legacy.js

@@ -45,13 +45,16 @@ function hook_ipv4v6(classname, data_id) {
               } else {
                   $(this).removeClass('hidden');
               }
-          }).promise().done(function(){
+          });
+          // select highest visible option
+          if (parseInt($("#"+selectlist_id).val()) > 32 && itemValue.indexOf(":") == -1) {
+            $("#"+selectlist_id+' option[value=32]').attr('selected','selected');
+          }
           // when select list uses selectpicker, refresh
           if ($("#"+selectlist_id).hasClass('selectpicker')) {
             $("#"+selectlist_id).selectpicker('refresh');
           }
         });
-        });
       }
       // trigger initial onChange event
       $("#"+$(this).data(data_id)).change();