.    @param[out] FileHandle        On exit, points to the file handle corresponding to the root directory on the                                  device.      @retval EFI_SUCCESS           Root opened successfully.    @retval EFI_NOT_FOUND         EFI_SIMPLE_FILE_SYSTEM could not be found or the root directory                                  could not be opened.    @retval EFI_VOLUME_CORRUPTED  The data structures in the volume were corrupted.    @retval EFI_DEVICE_ERROR      The device had an error.  **/  typedef  EFI_STATUS  (EFIAPI *EFI_SHELL_OPEN_ROOT