ARM: dts: Add ddc i2c reference to veyron

The ddc-i2c-bus property was missing from the veyron dtsi file since
downstream the ddc-i2c-bus was still being specified in rk3288.dtsi and
nobody noticed when the veyron dtsi was sent upstream.  Add it.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>