When AC power is not connected, EC doesn't update battery information in
mapped memory. This makes battery information unavailable is AC is not
present when EC boots.
BUG=chrome-os-partner:12858
TEST=Unplug AC and reset EC. Run ectool and check we can see battery
info.
BRANCH=link
Change-Id: I23339962a6aa1bbbf6806c1184b96e949466208f
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/30820
Reviewed-by: Rong Chang <rongchang@chromium.org>