rtc: mt2712: remove unnecessary error string

Remove the unnecessary error string as the core will already display error
messages when registration fails (i.e. never).

Link: https://lore.kernel.org/r/20200415200021.157118-1-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-mt2712.c

@@ -354,13 +354,7 @@ static int mt2712_rtc_probe(struct platform_device *pdev)
 	mt2712_rtc->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 	mt2712_rtc->rtc->range_max = MT2712_RTC_TIMESTAMP_END_2127;
 
-	ret = rtc_register_device(mt2712_rtc->rtc);
-	if (ret) {
-		dev_err(&pdev->dev, "register rtc device failed\n");
-		return ret;
-	}
-
-	return 0;
+	return rtc_register_device(mt2712_rtc->rtc);
 }
 
 #ifdef CONFIG_PM_SLEEP