dt-bindings: soc: renesas: Document RZ/N2H (R9A09G087) SoC

dt-bindings: soc: renesas: Document RZ/N2H (R9A09G087) SoC

Add RZ/N2H (R9A09G087), its variants, and the rzn2h-evk evaluation board
in documentation.

Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250609203656.333138-2-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>