Use /dev/ttydrbcc for communication with the board controller. HYP-7965

This is provided by a new rule for udev (see
meta-hipos-kirkwood/recipes-core/systemd).

Signed-off-by: Angelika Tobisch <tobisch@dresearch-fe.de>
Change systemd bbappend to use PRINC.

We now have another bbappend for systemd in meta-hipos-kirkwood.
Using PRINC in both bbappends improves version handling.

Signed-off-by: Angelika Tobisch <tobisch@dresearch-fe.de>