thermal: sun8i: Use scoped device node handling to simplify error paths

Obtain the device node reference with scoped/cleanup.h to reduce error
handling and make the code a bit simpler.

Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://patch.msgid.link/20241010-b4-cleanup-h-of-node-put-thermal-v4-6-bfbe29ad81f4@linaro.org


Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>