ARM: dts: rockchip: add veyron-brain board

Similar to pinky, brain is a development model and probably also
nearing extinction. But to keep pinky from being lonely I'll keep
the two brain boards around as well, especially as they as well
have easily accessible dut-connectors.

Signed-off-by: Heiko Stuebner <heiko.stuebner@collabora.com>
For the license change:
Acked-by: Brian Norris <briannorris@chromium.org>