ARM: dts: rockchip: move rk3288-veryon display settings into a separate file

The chromebook .dtsi file contains common settings for veyron
Chromebooks with eDP displays. Some veyron devices with a display
aren't Chromebooks (e.g. 'tiger' aka 'AOpen Chromebase Mini'), move
display related bits from the chromebook .dtsi into a separate file
to avoid redundant DT settings.

The new file is included from the chromebook .dtsi and can be
included by non-Chromebook devices with a display.

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>