dt-bindings: Add vendor prefix for CDTech(H.K.) Electronics Limited

This adds a vendor prefix "cdtech" for CDTech(H.K.) Electronics Limited

Website: www.cdtech-lcd.com

Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180730231117.5631-2-giulio.benetti@micronovasrl.com