spi: dt-bindings: renesas,rzv2h-rspi: Document RZ/G3L SoC

spi: dt-bindings: renesas,rzv2h-rspi: Document RZ/G3L SoC

Document RSPI IP found on the RZ/G3L SoC. The RSPI IP is compatible with
the RZ/V2H RSPI IP, but has 2 clocks compared to 3 on RZ/V2H.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://patch.msgid.link/20260408085418.18770-2-biju.das.jz@bp.renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>