can: kvaser_pciefd: Add len8_dlc support

Add support for the Classical CAN raw DLC functionality to send and receive
DLC values from 9 .. 15.

Signed-off-by: Jimmy Assarsson <extja@kvaser.com>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/all/20230529134248.752036-13-extja@kvaser.com


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>