This change enables user to shutdown the system by shortly pressing power button (<10sec) before OS is loaded. Main use case is shutdown from recovery/broken screen. BUG=N/A TEST=Boot up into recovery screen on Sarien platform, press power button once, and system should shutdown immediatelly. Change-Id: I7655daf65ff058df7d9bad4567f74b4f4007acb4 Signed-off-by: Krzysztof Sywula <krzysztof.m.sywula@intel.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/31894 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Lijian Zhao <lijian.zhao@intel.com> Reviewed-by: Furquan Shaikh <furquan@google.com>