can: rcar_canfd: Add postdiv to struct rcar_canfd_hw_info

R-Car has a clock divider for CAN FD clock within the IP, whereas
it is not available on RZ/G2L.

Add postdiv variable to struct rcar_canfd_hw_info to take care of this
difference.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/all/20221027082158.95895-5-biju.das.jz@bp.renesas.com


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