BaseTools: Guid.xref doesn't specify the correct GUID value for Driver

BaseTools: Guid.xref doesn't specify the correct GUID value for Driver

In DSC, we can define the driver with the different FILE GUID. So this
driver name and its FILE GUID should also be listed in Build output
Guid.xref. But now, Guid.xref still lists the driver MODULE_GUID.

The case in Platform.dsc:
  MdeModulePkg/Universal/DriverSampleDxe/DriverSampleDxe.inf {
    <Defines>
      FILE_GUID = 3A4A354F-6935-40fa-B19C-500EEEBF0BC2
    <LibraryClasses>
      PcdLib|MdePkg/Library/BasePcdLibNull/BasePcdLibNull.inf
  }

Cc: Liming Gao <liming.gao@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Yunhua Feng <yunhuax.feng@intel.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>