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

drivers/pmdomain/rockchip/pm-domains.c

@@ -910,7 +910,7 @@ static int rockchip_pm_domain_probe(struct platform_device *pdev)
 	 * Prevent any rockchip_pmu_block() from racing with the remainder of
 	 * setup (clocks, register initialization).
 	 */
-	mutex_lock(&dmc_pmu_mutex);
+	guard(mutex)(&dmc_pmu_mutex);
 
 	for_each_available_child_of_node_scoped(np, node) {
 		error = rockchip_pm_add_one_domain(pmu, node);
@@ -943,13 +943,10 @@ static int rockchip_pm_domain_probe(struct platform_device *pdev)
 	if (!WARN_ON_ONCE(dmc_pmu))
 		dmc_pmu = pmu;
 
-	mutex_unlock(&dmc_pmu_mutex);
-
 	return 0;
 
 err_out:
 	rockchip_pm_domain_cleanup(pmu);
-	mutex_unlock(&dmc_pmu_mutex);
 	return error;
 }