rock-pi s devicetree and overlays

Armbian rockpis board uses the rockpis family which for the current and edge branch includes rockchip64-common.inc, which defines 6.6 as the KERNEL_MAJOR_MINOR and leaves KERNELSOURCE unset, which sets it to mainline, which is the linux stable tree.

IOW, the rockpi-s devicetree comes from mainline kernel: https://github.com/gregkh/linux/blob/linux-6.6.y/arch/arm64/boot/dts/rockchip/rk3308-rock-pi-s.dts (possible patched by https://github.com/armbian/build/tree/main/patch/kernel)