Adds a function that manages the video pipleline through ANX7808.
Adds a timer to debounce the cable detect signal.
Adds a workqueue on which management function runs.
BUG=chrome-os-partner:16196
TEST=Plug in HDMI connector to external monitor, power up, and see video.
Change-Id: I45440b43033304e1703113ec2e949ca39ad17071
Signed-off-by: Jeremy Thorpe <jeremyt@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/49561