REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2668 SetMode will fail in some case. for example, without XServer. Should handle these case when SetMode fail. If we don't handle it, it will Segmentation fault. Reviewed-by: Ray Ni <ray.ni@intel.com> Signed-off-by: Guomin Jiang <guomin.jiang@intel.com>