Parallel run the function GetStackBase for all APs for better performance. Reviewed-by: Ray Ni <ray.ni@intel.com> Cc: Laszlo Ersek <lersek@redhat.com> Cc: Rahul Kumar <rahul1.kumar@intel.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Cc: Star Zeng <star.zeng@intel.com> Cc: Daoxiang Li <daoxiang.li@intel.com> Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>