Moving the devices to their own module makes it easier to add tests that
use them.
Change-Id: I61bfef4037d16b20145b5fddce604835cdc4f67b
Signed-off-by: Dylan Reid <dgreid@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/706559
Reviewed-by: Zach Reizner <zachr@chromium.org>
