Add HII definitions from UEFI 2.6 for HII Image Variability and PNG Blocks Cc: Yonghong Zhu <yonghong.zhu@intel.com> Cc: Liming Gao <liming.gao@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Samer El-Haj-Mahmoud <elhaj@hpe.com> Reviewed-by: Dandan Bi <dandan.bi@intel.com> Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>