further improvements for sysimage-v3
- use mke2fs when running as root until we made genext2fs faster
- remove leftover files from kernel and reform-tools which both now live in reform-debian-packages
- fix flash-kernel config
- use uboot from ci pipeline instead of building it ourselves
- split up packages into five sets for easier editing
- create a dedicated partition for /boot
- chown files to be owned by root
Edited by Johannes Schauer Marin Rodrigues