can: sja1000: Add support for RZ/N1 SJA1000 CAN Controller

The SJA1000 CAN controller on RZ/N1 SoC has no clock divider register
(CDR) support compared to others.

This patch adds support for RZ/N1 SJA1000 CAN Controller, by adding
SoC specific compatible to handle this difference as well as using
clk framework to retrieve the CAN clock frequency.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/all/20220710115248.190280-7-biju.das.jz@bp.renesas.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>