can: rcar_canfd: Add max_cftml variable to struct rcar_canfd_hw_info

can: rcar_canfd: Add max_cftml variable to struct rcar_canfd_hw_info

R-Car Gen3 has CFTML max positional value is 15 whereas on R-Car Gen4 it
is 31. Add a max_cftml variable to struct rcar_canfd_hw_info to handle
this difference.

While at it, rename the parameter x->cftml in RCANFD_CFCC_CFTML macro to
make it clear.

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://patch.msgid.link/20250417054320.14100-12-biju.das.jz@bp.renesas.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>