Remove Canute braille display support.

The Canute driver was experimental only, so this won't affect users.
The driver was incorrectly identifying Arduino Leonardo as Canute,
which *was* affecting users. We need to fix that before re-landing.

BUG=chromium:739176
TEST=Manually test Canute no longer triggers spoken feedback

Change-Id: I94d6365440da50f2ebd10aef0ff95b214438271f
Reviewed-on: https://chromium-review.googlesource.com/648093
Commit-Ready: Dominic Mazzoni <dmazzoni@chromium.org>
Tested-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: David Tseng <dtseng@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
3 files changed