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>

drivers/char/rtc.c

@@ -1125,11 +1125,10 @@ static int rtc_proc_show(struct seq_file *seq, void *v)
 	 * time or for Universal Standard Time (GMT). Probably local though.
 	 */
 	seq_printf(seq,
-		   "rtc_time\t: %02d:%02d:%02d\n"
-		   "rtc_date\t: %04d-%02d-%02d\n"
+		   "rtc_time\t: %ptRt\n"
+		   "rtc_date\t: %ptRd\n"
 		   "rtc_epoch\t: %04lu\n",
-		   tm.tm_hour, tm.tm_min, tm.tm_sec,
-		   tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, epoch);
+		   &tm, &tm, epoch);
 
 	get_rtc_alm_time(&tm);