PM / sleep: fix device reference leak in test_suspend

Make sure to drop the reference taken by class_find_device() after
opening the RTC device.

Fixes: 77437fd (pm: boot time suspend selftest)
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

kernel/power/suspend_test.c

@@ -203,8 +203,10 @@ static int __init test_suspend(void)
 
 	/* RTCs have initialized by now too ... can we use one? */
 	dev = class_find_device(rtc_class, NULL, NULL, has_wakealarm);
-	if (dev)
+	if (dev) {
 		rtc = rtc_class_open(dev_name(dev));
+		put_device(dev);
+	}
 	if (!rtc) {
 		printk(warn_no_rtc);
 		return 0;