rtc: Switch to use %ptR

Use %ptR instead of open coded variant to print content of
struct rtc_time in human readable format.

Note, we drop the validation option. This is only used in
a deprecated ABI and is mostly wrong as many RTCs will still be valid
after 2100.

Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
diff --git a/drivers/rtc/rtc-sysfs.c b/drivers/rtc/rtc-sysfs.c
index 9746c32..a8f22ee7 100644
--- a/drivers/rtc/rtc-sysfs.c
+++ b/drivers/rtc/rtc-sysfs.c
@@ -39,12 +39,10 @@
 	struct rtc_time tm;
 
 	retval = rtc_read_time(to_rtc_device(dev), &tm);
-	if (retval == 0) {
-		retval = sprintf(buf, "%04d-%02d-%02d\n",
-			tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
-	}
+	if (retval)
+		return retval;
 
-	return retval;
+	return sprintf(buf, "%ptRd\n", &tm);
 }
 static DEVICE_ATTR_RO(date);
 
@@ -55,12 +53,10 @@
 	struct rtc_time tm;
 
 	retval = rtc_read_time(to_rtc_device(dev), &tm);
-	if (retval == 0) {
-		retval = sprintf(buf, "%02d:%02d:%02d\n",
-			tm.tm_hour, tm.tm_min, tm.tm_sec);
-	}
+	if (retval)
+		return retval;
 
-	return retval;
+	return sprintf(buf, "%ptRt\n", &tm);
 }
 static DEVICE_ATTR_RO(time);