can: mark led trigger as broken

The driver was suggested for deletion as it implements a subset of the
netdev trigger. It's in the way for further cleanups in the trigger
code but doesn't get an Ack by someone who can actually test and confirm
that the netdev trigger works for can devices. So marking as broken to
get forward with the cleanups.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>