can: c_can: remove wrong comment

The comment referred to a status (warning) other than the one that was
being managed (active error).

Link: https://lore.kernel.org/all/20220716170112.2020291-1-dario.binacchi@amarulasolutions.com


Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>