rtc: ftrtc010: drop needless struct ftrtc010_rtc::rtc_dev member

The memory pointed to by the ::rtc_dev member is managed via devres,
and no code in this driver uses it past _probe().

We can drop it from the structure and just use a local temporary
variable, reducing runtime memory consumption by a few bytes.

Reviewed-by: Linus Walleij <[e-mail]>
Signed-off-by: André Draszik <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexandre Belloni <[e-mail]>

drivers/rtc/rtc-ftrtc010.c

···
 MODULE_ALIAS("platform:" DRV_NAME);
 
 struct ftrtc010_rtc {
-	struct rtc_device	*rtc_dev;
 	void __iomem		*rtc_base;
 	int			rtc_irq;
 	struct clk		*pclk;
···
 	struct ftrtc010_rtc *rtc;
 	struct device *dev = &pdev->dev;
 	struct resource *res;
+	struct rtc_device *rtc_dev;
 	int ret;
 
 	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
···
 		goto err_disable_extclk;
 	}
 
-	rtc->rtc_dev = devm_rtc_allocate_device(dev);
-	if (IS_ERR(rtc->rtc_dev)) {
-		ret = PTR_ERR(rtc->rtc_dev);
+	rtc_dev = devm_rtc_allocate_device(dev);
+	if (IS_ERR(rtc_dev)) {
+		ret = PTR_ERR(rtc_dev);
 		goto err_disable_extclk;
 	}
 
-	rtc->rtc_dev->ops = &ftrtc010_rtc_ops;
+	rtc_dev->ops = &ftrtc010_rtc_ops;
 
 	sec  = readl(rtc->rtc_base + FTRTC010_RTC_SECOND);
 	min  = readl(rtc->rtc_base + FTRTC010_RTC_MINUTE);
 	hour = readl(rtc->rtc_base + FTRTC010_RTC_HOUR);
 	days = readl(rtc->rtc_base + FTRTC010_RTC_DAYS);
 
-	rtc->rtc_dev->range_min = (u64)days * 86400 + hour * 3600 +
-				  min * 60 + sec;
-	rtc->rtc_dev->range_max = U32_MAX + rtc->rtc_dev->range_min;
+	rtc_dev->range_min = (u64)days * 86400 + hour * 3600 + min * 60 + sec;
+	rtc_dev->range_max = U32_MAX + rtc_dev->range_min;
 
 	ret = devm_request_irq(dev, rtc->rtc_irq, ftrtc010_rtc_interrupt,
 			       IRQF_SHARED, pdev->name, dev);
 	if (unlikely(ret))
 		goto err_disable_extclk;
 
-	return devm_rtc_register_device(rtc->rtc_dev);
+	return devm_rtc_register_device(rtc_dev);
 
 err_disable_extclk:
 	clk_disable_unprepare(rtc->extclk);