arm64: dts: rockchip: Add basic support for Kobol's Helios64

The hardware is described in detail on Kobol's wiki at
https://wiki.kobol.io/helios64/intro/

.

Up to now the following peripherals are working:

 - UART
 - Micro-SD card
 - eMMC
 - ethernet port 1
 - status LED
 - temperature sensor on i2c bus 2

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Link: https://lore.kernel.org/r/20201014200030.845759-3-uwe@kleine-koenig.org


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