This adds USB port control to charger task. For now, it only senses
attached device type and log it to console.
BUG=chrome-os-partner:14319
TEST=Attach/detach charger and see console output.
BRANCH=none
Change-Id: I1218d520c292d9d398c868122ae3876d3fc889bc
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/40078
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>