ARM: dts: rockchip: Add GPU node for RK3128

RK3128 SoCs have Mali400 MP2 GPU.
Add the respective device tree node and the correspondending opp-table.

The frequencies and voltages of the opp-table have been taken from
downstream kernel.

Signed-off-by: Alex Bee <knaerzche@gmail.com>
Link: https://lore.kernel.org/r/20231204153547.97877-3-knaerzche@gmail.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>