If FirmwareVolumeShadow PPI is available, then use it to
shadow FVs to memory. Otherwise fallback to CopyMem().
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Signed-off-by: Patel Umang <umang.patel@intel.com>
Reviewed-by: Jian J Wang <jian.j.wang@intel.com>