This patch adds code to control the power LED.
BUG=b:37646390
BRANCH=none
TEST=Verify LED turns green, red, amber, off. Verify LED turns green
or off when chipset is on or off, respectively.
Change-Id: I1d7940d9bb4414d97c541ead802efeb8f279533e
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/486947
