dt-bindings: soc: renesas: Document Renesas RZ/V2N SoC variants and EVK

dt-bindings: soc: renesas: Document Renesas RZ/V2N SoC variants and EVK

Document the Renesas RZ/V2N (R9A09G056) SoC variants, distinguishing
between configurations with and without specific hardware features such
as GPU, ISP, and cryptographic extensions. Also, document the
"renesas,rzv2n-evk" compatible string for the RZ/V2N EVK board.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250407191628.323613-2-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>