PM: Make dev_pm_get_subsys_data() always return 0 on success

Commits 1d5fcfec (PM / Domains: Add device domain data reference
counter) and 62d44902 (PM / Domains: Allow device callbacks to be
added at any time) added checks for the return value of
dev_pm_get_subsys_data(), but those checks were incorrect, because
that function returned 1 on success in some cases.

Since all of the existing users of dev_pm_get_subsys_data() don't use
the positive value returned by it on success, change its definition
so that it always returns 0 when successful.
Reported-by: Heiko Stübner <heiko@sntech.de>
Reported-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

drivers/base/power/clock_ops.c

@@ -169,8 +169,7 @@ void pm_clk_init(struct device *dev)
  */
 int pm_clk_create(struct device *dev)
 {
-	int ret = dev_pm_get_subsys_data(dev);
-	return ret < 0 ? ret : 0;
+	return dev_pm_get_subsys_data(dev);
 }
 
 /**

drivers/base/power/common.c

@@ -24,7 +24,6 @@
 int dev_pm_get_subsys_data(struct device *dev)
 {
 	struct pm_subsys_data *psd;
-	int ret = 0;
 
 	psd = kzalloc(sizeof(*psd), GFP_KERNEL);
 	if (!psd)
@@ -40,7 +39,6 @@ int dev_pm_get_subsys_data(struct device *dev)
 		dev->power.subsys_data = psd;
 		pm_clk_init(dev);
 		psd = NULL;
-		ret = 1;
 	}
 
 	spin_unlock_irq(&dev->power.lock);
@@ -48,7 +46,7 @@ int dev_pm_get_subsys_data(struct device *dev)
 	/* kfree() verifies that its argument is nonzero. */
 	kfree(psd);
 
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data);