rtc: sysfs: fix a cast removing the const attribute

The char pointer buf_ptr is assigned an address from a const char
pointer buf (parameter of wakealarm_store).
The data pointer by buf_ptr is never modified.
So casting it to a (char *) is useless.

This patch remove this cast, and transform buf_ptr to a const char pointer.
Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-sysfs.c

@@ -160,7 +160,7 @@ wakealarm_store(struct device *dev, struct device_attribute *attr,
 	unsigned long push = 0;
 	struct rtc_wkalrm alm;
 	struct rtc_device *rtc = to_rtc_device(dev);
-	char *buf_ptr;
+	const char *buf_ptr;
 	int adjust = 0;
 
 	/* Only request alarms that trigger in the future.  Disable them
@@ -171,7 +171,7 @@ wakealarm_store(struct device *dev, struct device_attribute *attr,
 		return retval;
 	rtc_tm_to_time(&alm.time, &now);
 
-	buf_ptr = (char *)buf;
+	buf_ptr = buf;
 	if (*buf_ptr == '+') {
 		buf_ptr++;
 		if (*buf_ptr == '=') {