can: rcar_canfd: Update bit rate constants for RZ/G3E and R-Car Gen4

The calculation formula for nominal bit rate of classical CAN is the same as
that of nominal bit rate of CANFD on the RZ/G3E and R-Car Gen4 SoCs
compared to other SoCs. Update nominal bit rate constants.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20250908120940.147196-2-biju.das.jz@bp.renesas.com
[mkl: slightly improve wording of commit message]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Author: bijudas

drivers/net/can/rcar/rcar_canfd.c

@@ -1912,7 +1912,10 @@ static int rcar_canfd_channel_probe(struct rcar_canfd_global *gpriv, u32 ch,
 		priv->can.fd.do_get_auto_tdcv = rcar_canfd_get_auto_tdcv;
 	} else {
 		/* Controller starts in Classical CAN only mode */
-		priv->can.bittiming_const = &rcar_canfd_bittiming_const;
+		if (gpriv->info->shared_can_regs)
+			priv->can.bittiming_const = gpriv->info->nom_bittiming;
+		else
+			priv->can.bittiming_const = &rcar_canfd_bittiming_const;
 		priv->can.ctrlmode_supported = CAN_CTRLMODE_BERR_REPORTING;
 	}