rtc: aspeed: drop needless struct aspeed_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.

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-aspeed.c

···
 #include <linux/io.h>
 
 struct aspeed_rtc {
-	struct rtc_device *rtc_dev;
 	void __iomem *base;
 };
 
···
 static int aspeed_rtc_probe(struct platform_device *pdev)
 {
 	struct aspeed_rtc *rtc;
+	struct rtc_device *rtc_dev;
 
 	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
 	if (!rtc)
···
 	if (IS_ERR(rtc->base))
 		return PTR_ERR(rtc->base);
 
-	rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
-	if (IS_ERR(rtc->rtc_dev))
-		return PTR_ERR(rtc->rtc_dev);
+	rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(rtc_dev))
+		return PTR_ERR(rtc_dev);
 
 	platform_set_drvdata(pdev, rtc);
 
-	rtc->rtc_dev->ops = &aspeed_rtc_ops;
-	rtc->rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900;
-	rtc->rtc_dev->range_max = 38814989399LL; /* 3199-12-31 23:59:59 */
+	rtc_dev->ops = &aspeed_rtc_ops;
+	rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900;
+	rtc_dev->range_max = 38814989399LL; /* 3199-12-31 23:59:59 */
 
-	return devm_rtc_register_device(rtc->rtc_dev);
+	return devm_rtc_register_device(rtc_dev);
 }
 
 static const struct of_device_id aspeed_rtc_match[] = {