Also add snprintf(), and %X format code.
BUG=chrome-os-partner:10206
TEST=timerinfo; should print correctly. 'ectool battery' on host side should print same serial as 'battery' on EC console.
Change-Id: I5c9f69d1a20ee5d0a59440c122655adbf62c9aea
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/24635
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Rong Chang <rongchang@chromium.org>
