dt-bindings: touchscreen: Add HY46XX bindings

This adds device tree bindings for the Hycon HY46XX touchscreen series.

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210413144446.2277817-3-giulio.benetti@benettiengineering.com


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>