dualboot: add truedualboot support

Change-Id: I33dec96da48700307550be05807a6b78d5e8b08c
dualboot: add menu item under advanced to set bootmode
- also refresh dualboot entries everytime before calling 'get_filtered_menu_selection'
  to sync changes

Change-Id: I717cef001733d5edf1edea73ecc724edb1fd3fa2