rtc: sd2405al: drop needless struct sd2405al::rtc member

The memory pointed to by the ::rtc 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.

Tested-by: Tóth János <gomba007@gmail.com>
Signed-off-by: André Draszik <andre.draszik@linaro.org>
Link: https://lore.kernel.org/r/20250304-rtc-cleanups-v2-13-d4689a71668c@linaro.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: andred

drivers/rtc/rtc-sd2405al.c

@@ -42,7 +42,6 @@
 
 struct sd2405al {
 	struct device		*dev;
-	struct rtc_device	*rtc;
 	struct regmap		*regmap;
 };
 
@@ -167,6 +166,7 @@ static const struct regmap_config sd2405al_regmap_conf = {
 static int sd2405al_probe(struct i2c_client *client)
 {
 	struct sd2405al *sd2405al;
+	struct rtc_device *rtc;
 	int ret;
 
 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
@@ -182,17 +182,17 @@ static int sd2405al_probe(struct i2c_client *client)
 	if (IS_ERR(sd2405al->regmap))
 		return PTR_ERR(sd2405al->regmap);
 
-	sd2405al->rtc = devm_rtc_allocate_device(&client->dev);
-	if (IS_ERR(sd2405al->rtc))
-		return PTR_ERR(sd2405al->rtc);
+	rtc = devm_rtc_allocate_device(&client->dev);
+	if (IS_ERR(rtc))
+		return PTR_ERR(rtc);
 
-	sd2405al->rtc->ops = &sd2405al_rtc_ops;
-	sd2405al->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
-	sd2405al->rtc->range_max = RTC_TIMESTAMP_END_2099;
+	rtc->ops = &sd2405al_rtc_ops;
+	rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
+	rtc->range_max = RTC_TIMESTAMP_END_2099;
 
 	dev_set_drvdata(&client->dev, sd2405al);
 
-	ret = devm_rtc_register_device(sd2405al->rtc);
+	ret = devm_rtc_register_device(rtc);
 	if (ret < 0)
 		return ret;