dt-bindings: can: nxp,sja1000: Document RZ/N1 power-domains support

Document RZ/N1 power-domains support. Also update the example with
power-domains property.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/all/20220830164518.1381632-2-biju.das.jz@bp.renesas.com


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