Add a dialog box with help message when user changes the state of "Attempt Secure Boot" check box.

Signed-off-by: Fu Siyuan <siyuan.fu@intel.com>
Reviewed-by: Ye Ting  <ting.ye@intel.com>
Reviewed-by: Dong Guo <guo.dong@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13733 6f19259b-4bc3-4df7-8a09-765794883524

SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigImpl.c

@@ -2396,6 +2396,13 @@ SecureBootCallback (
             NULL
             );
           Status = EFI_UNSUPPORTED;
+        } else {
+          CreatePopUp (
+            EFI_LIGHTGRAY | EFI_BACKGROUND_BLUE,
+            &Key,
+            L"Secure boot configuration is changed, please reset the platform to take effect!",
+            NULL
+            );
         }
         *ActionRequest = EFI_BROWSER_ACTION_REQUEST_FORM_APPLY; 
       }