rtc: omap: call rtc_nvmem_register()

Call rtc_nvmem_register instead of letting the core do it and stop using
the nvmem_config member of struct rtc_device.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-omap.c

@@ -850,7 +850,6 @@ static int omap_rtc_probe(struct platform_device *pdev)
 
 	rtc->rtc->ops = &omap_rtc_ops;
 	omap_rtc_nvmem_config.priv = rtc;
-	rtc->rtc->nvmem_config = &omap_rtc_nvmem_config;
 
 	/* handle periodic and alarm irqs */
 	ret = devm_request_irq(&pdev->dev, rtc->irq_timer, rtc_irq, 0,
@@ -886,6 +885,8 @@ static int omap_rtc_probe(struct platform_device *pdev)
 	if (ret)
 		goto err;
 
+	rtc_nvmem_register(rtc->rtc, &omap_rtc_nvmem_config);
+
 	return 0;
 
 err: