pmdomain: rockchip: Simplify locking with guard()

Simplify error handling (smaller error handling) over locks with
guard().

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20240823-cleanup-h-guard-pm-domain-v1-2-8320722eaf39@linaro.org


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>