rtc: rtc-lp8788: use devm_rtc_device_register()

devm_rtc_device_register() is device managed and makes cleanup
paths simpler.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/rtc-lp8788.c

@@ -299,7 +299,7 @@ static int lp8788_rtc_probe(struct platform_device *pdev)
 
 	device_init_wakeup(dev, 1);
 
-	rtc->rdev = rtc_device_register("lp8788_rtc", dev,
+	rtc->rdev = devm_rtc_device_register(dev, "lp8788_rtc",
 					&lp8788_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rtc->rdev)) {
 		dev_err(dev, "can not register rtc device\n");
@@ -314,9 +314,6 @@ static int lp8788_rtc_probe(struct platform_device *pdev)
 
 static int lp8788_rtc_remove(struct platform_device *pdev)
 {
-	struct lp8788_rtc *rtc = platform_get_drvdata(pdev);
-
-	rtc_device_unregister(rtc->rdev);
 	platform_set_drvdata(pdev, NULL);
 
 	return 0;