dt-bindings: can: renesas,rcar-canfd: Document RZ/G3E support

dt-bindings: can: renesas,rcar-canfd: Document RZ/G3E support

Document support for the CAN-FD Interface on the RZ/G3E (R9A09G047) SoC,
which supports up to six channels.

The CAN-FD module on RZ/G3E is very similar to the one on both R-Car V4H
and RZ/G2L, but differs in some hardware parameters:
 * No external clock, but instead has ram clock.
 * Support up to 6 channels.
 * 20 interrupts.

Reviewed-by: "Rob Herring (Arm)" <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://patch.msgid.link/20250417054320.14100-3-biju.das.jz@bp.renesas.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>