[ROCKCHIP] add rk3568 and rk3399 support, fix bugs
- add Things support for rk3568, rk3399 (also tested on px30)
- inherit edgehog.bbclass in Things image
- use rockchip-provided mkimage instead of the yocto default for all rockchip boards
Hi all, Gitlab will be set in maintenance mode on Friday 29/11/2024 from 08:45 AM CET with the intention of finishing by the 10:45 PM CET of Friday 29/11/2024