rtc: rtc-m41t93: 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-m41t93.c

@@ -184,8 +184,8 @@ static int m41t93_probe(struct spi_device *spi)
 		return -ENODEV;
 	}
 
-	rtc = rtc_device_register(m41t93_driver.driver.name,
-		&spi->dev, &m41t93_rtc_ops, THIS_MODULE);
+	rtc = devm_rtc_device_register(&spi->dev, m41t93_driver.driver.name,
+					&m41t93_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);
 
@@ -197,11 +197,6 @@ static int m41t93_probe(struct spi_device *spi)
 
 static int m41t93_remove(struct spi_device *spi)
 {
-	struct rtc_device *rtc = spi_get_drvdata(spi);
-
-	if (rtc)
-		rtc_device_unregister(rtc);
-
 	return 0;
 }