dt-bindings: soc: renesas: renesas-soc: Add pattern for gray-hawk

Add a pattern for the Renesas Gray Hawk Single board (based on the R-Car
V4M 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/r/20240227220930.213703-1-prabhakar.mahadev-lad.rj@bp.renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>