change default parameter value to None since the parameter isn't used. remove temporary dictionary and just do the reaplce call. Cc: Liming Gao <liming.gao@intel.com> Cc: Yonghong Zhu <yonghong.zhu@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Jaben Carsey <jaben.carsey@intel.com> Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>