Add a test of checking EC battery status report

This test checks if EC correctly report battery status to kernel.

BUG=chrome-os-partner:9188
TEST=Test passed.

Change-Id: Ib1d633de0078ecd6e7dff0a2e89d7aa04b1e4405
Reviewed-on: https://gerrit.chromium.org/gerrit/24169
Reviewed-by: Tom Wai-Hong Tam <waihong@chromium.org>
Tested-by: Vic Yang <victoryang@chromium.org>
Commit-Ready: Vic Yang <victoryang@chromium.org>
2 files changed