This was copied from libinput and made sense while libratbag was a library -
we want "unhandled" messages to end up somewhere and stderr is the most likely
candidate here.
Now that we always run within ratbagd and it's all effectively inseperable,
just log to stdout for anything below error.
The switch statement was reformatted for consistency, only the ERROR case has
changed code.
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>