arm: dts: rockchip: Add dts for rk3308 evb

Add dts for rk3308 evb, sync from the linux kernel
upstream list [0].

[0]https://patchwork.kernel.org/patch/11201555/



Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>