PTXdist: remove useless and unmaintained files

Both files just confuse new users. Their content is at least
four years old.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
rc-once: enter rescue mode if rc-once fails

rc-once should not fail. So let the user investigate in rescue mode.

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>