can: rcar_canfd: Fix R-Car Gen4 CFCC.CFTML field width

On R-Car Gen4 CAN_FD variants, the Common FIFO TX Message Buffer Link
(CFTML) field in the Common FIFO Configuration / Control Register (CCFC)
register is one bit wider than on older variants.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/all/9c37aaa799a2391be272dbaa474379cf9a7af147.1674499048.git.geert+renesas@glider.be


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