arm64: dts: rockchip: Add devicetree for board roc-rk3308-cc

ROC-RK3308-CC is a rk3308 based board designed by Firelfy,
with eMMC and 256MB DDR3 and RTL8188 Wifi on board.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Link: https://lore.kernel.org/r/20191030072811.29882-1-andy.yan@rock-chips.com


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