rtc: pm8xxx: convert to devm_rtc_allocate_device

This allows further improvement of the driver. Also remove the unnecessary
error string as the core will already display error messages.

Link: https://lore.kernel.org/r/20200306073758.58050-1-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-pm8xxx.c

@@ -486,13 +486,11 @@ static int pm8xxx_rtc_probe(struct platform_device *pdev)
 	device_init_wakeup(&pdev->dev, 1);
 
 	/* Register the RTC device */
-	rtc_dd->rtc = devm_rtc_device_register(&pdev->dev, "pm8xxx_rtc",
-					       &pm8xxx_rtc_ops, THIS_MODULE);
-	if (IS_ERR(rtc_dd->rtc)) {
-		dev_err(&pdev->dev, "%s: RTC registration failed (%ld)\n",
-			__func__, PTR_ERR(rtc_dd->rtc));
+	rtc_dd->rtc = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(rtc_dd->rtc))
 		return PTR_ERR(rtc_dd->rtc);
-	}
+
+	rtc_dd->rtc->ops = &pm8xxx_rtc_ops;
 
 	/* Request the alarm IRQ */
 	rc = devm_request_any_context_irq(&pdev->dev, rtc_dd->rtc_alarm_irq,
@@ -504,9 +502,7 @@ static int pm8xxx_rtc_probe(struct platform_device *pdev)
 		return rc;
 	}
 
-	dev_dbg(&pdev->dev, "Probe success !!\n");
-
-	return 0;
+	return rtc_register_device(rtc_dd->rtc);
 }
 
 #ifdef CONFIG_PM_SLEEP