dt-bindings: pinctrl: renesas: Document RZ/V2N SoC

dt-bindings: pinctrl: renesas: Document RZ/V2N SoC

Add documentation for the pin controller found on the Renesas RZ/V2N
(R9A09G056) SoC. The RZ/V2N PFC differs slightly from the RZ/G2L family
and is almost identical to the RZ/V2H(P) SoC, except that the RZ/V2H(P) SoC
has an additional dedicated pin.

To account for this, a SoC-specific compatible string,
'renesas,r9a09g056-pinctrl', is introduced for the RZ/V2N SoC.

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/20250407191628.323613-10-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>