dt-bindings: phy: renesas,usb2-phy: Document RZ/V2N SoC support

Document support for the USB2.0 phy found on the Renesas RZ/V2N
(R9A09G056) SoC. The USB2.0 phy is functionally identical to that on the
RZ/V2H(P) SoC, so no driver changes are needed. The existing
`renesas,usb2-phy-r9a09g057` compatible will be used as a fallback
for the RZ/V2N SoC.

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/r/20250528133858.168582-1-prabhakar.mahadev-lad.rj@bp.renesas.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>