can: bcm: fix hrtimer/tasklet termination in bcm op removal

When removing a bcm tx operation either a hrtimer or a tasklet might run.
As the hrtimer triggers its associated tasklet and vice versa we need to
take care to mutually terminate both handlers.

Reported-by: Michael Josenhans <michael.josenhans@web.de>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Tested-by: Michael Josenhans <michael.josenhans@web.de>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>