pmdomain: rockchip: cleanup mutex handling in rockchip_pd_power

Use the cleanup infrastructure to handle the mutex, which
slightly improve code readability for this function.

Reviewed-by: Heiko Stuebner <[email protected]>
Tested-by: Heiko Stuebner <[email protected]>
Tested-by: Adrian Larumbe <[email protected]> # On Rock 5B
Signed-off-by: Sebastian Reichel <[email protected]>
Link: https://lore.kernel.org/r/20250220-rk3588-gpu-pwr-domain-regulator-v6-2-a4f9c24e5b81@kernel.org
Signed-off-by: Ulf Hansson <[email protected]>

Author: sre

drivers/pmdomain/rockchip/pm-domains.c

@@ -583,13 +583,12 @@ static int rockchip_pd_power(struct rockchip_pm_domain *pd, bool power_on)
 	struct rockchip_pmu *pmu = pd->pmu;
 	int ret;
 
-	mutex_lock(&pmu->mutex);
+	guard(mutex)(&pmu->mutex);
 
 	if (rockchip_pmu_domain_is_on(pd) != power_on) {
 		ret = clk_bulk_enable(pd->num_clks, pd->clks);
 		if (ret < 0) {
 			dev_err(pmu->dev, "failed to enable clocks\n");
-			mutex_unlock(&pmu->mutex);
 			return ret;
 		}
 
@@ -615,7 +614,6 @@ static int rockchip_pd_power(struct rockchip_pm_domain *pd, bool power_on)
 		clk_bulk_disable(pd->num_clks, pd->clks);
 	}
 
-	mutex_unlock(&pmu->mutex);
 	return 0;
 }