ARM: dts: rockchip: add soc-specific compatibles for rk3036 SoCs

While drivers will bind to the generic compatible values, this enables
the use of more specialized drivers in the future, if the need arises.

Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>