dt-bindings: thermal: r9a09g047-tsu: Document RZ/V2N TSU

dt-bindings: thermal: r9a09g047-tsu: Document RZ/V2N TSU

The Renesas RZ/V2N SoC includes a Thermal Sensor Unit (TSU) block designed
to measure the junction temperature. The device provides real-time
temperature measurements for thermal management, utilizing two dedicated
channels for temperature sensing.

The Renesas RZ/V2N SoC is using the same TSU IP found on the RZ/G3E SoC,
the only difference being that it has two channels instead of one.

Add new compatible string "renesas,r9a09g056-tsu" for RZ/V2N and use
"renesas,r9a09g047-tsu" as a fallback compatible to indicate hardware
compatibility with the RZ/G3E implementation.

Signed-off-by: Ovidiu Panait <ovidiu.panait.rb@renesas.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20251209091115.8541-2-ovidiu.panait.rb@renesas.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>