MdeModulePkg/BootMaintUiLib: Update menus when open BMM form

BootMaintenanceManagerUiLib depend on the LeagcyBootMaintUiLib to show the
legacy menus. So we need to do the actions related to LegacyUi in BMM
after the LeagcyBootMaintUiLib have been initialized. So now : 1). update
menus (including legacy menus), 2) re-scan boot options (including legacy
boot option) when opening the BMM form. We think when opening BMM form,
the LeagcyBootMaintUiLib must have been initialized.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

MdeModulePkg/Library/BootMaintenanceManagerUiLib/BootMaintenanceManager.vfr

@@ -1,7 +1,7 @@
 ///** @file
 //  Boot Maintenance Utility Formset
 //
-//  Copyright (c) 2004 - 2015, Intel Corporation. All rights reserved.<BR>
+//  Copyright (c) 2004 - 2016, Intel Corporation. All rights reserved.<BR>
 //  This program and the accompanying materials
 //  are licensed and made available under the terms and conditions of the BSD License
 //  which accompanies this distribution.  The full text of the license may be found at
@@ -27,6 +27,17 @@ formset
 
   form formid = FORM_MAIN_ID,
        title = STRING_TOKEN(STR_FORM_MAIN_TITLE);
+       //
+       // Add this invisible text in order to indicate enter Boot Maintenance Manager form.
+       // To trigger the form open action.
+       //
+       suppressif TRUE;
+          text
+              help  = STRING_TOKEN(STR_NONE),
+              text  = STRING_TOKEN(STR_NONE),
+              flags = INTERACTIVE,
+              key   = KEY_VALUE_TRIGGER_FORM_OPEN_ACTION;
+       endif;
          
     label LABEL_FORM_MAIN_START;
     //