In the patch

    d9b081e3 ("can: flexcan: remove ack_grp and ack_bit handling from driver")

the unused ack_grp and ack_bit were removed from the driver. However in the
comment, the "req_bit" was accidentally removed, too.

This patch adds back the "req_bit" bit.

Fixes: d9b081e3 ("can: flexcan: remove ack_grp and ack_bit handling from driver")
Reported-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Link: http://lore.kernel.org/r/20201014114810.2911135-1-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>