PM / Domains: Verify PM domain type in dev_pm_genpd_set_performance_state()

The dev_pm_genpd_set_performance_state() could in principle be called for a
device that has a different PM domain type attached than a genpd. This
would lead to a problem as dev_to_genpd() uses the container_of macro.

Address this problem by using dev_to_genpd_safe() instead.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/domain.c

@@ -380,8 +380,8 @@ int dev_pm_genpd_set_performance_state(struct device *dev, unsigned int state)
 	unsigned int prev;
 	int ret;
 
-	genpd = dev_to_genpd(dev);
-	if (IS_ERR(genpd))
+	genpd = dev_to_genpd_safe(dev);
+	if (!genpd)
 		return -ENODEV;
 
 	if (unlikely(!genpd->set_performance_state))