kdb: Switch to use %ptTs

Use %ptTs instead of open-coded variant to print contents
of time64_t type in human readable form.

Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: kgdb-bugreport@lists.sourceforge.net
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210511153958.34527-2-andriy.shevchenko@linux.intel.com

kernel/debug/kdb/kdb_main.c

@@ -2488,7 +2488,6 @@ static void kdb_sysinfo(struct sysinfo *val)
 static int kdb_summary(int argc, const char **argv)
 {
 	time64_t now;
-	struct tm tm;
 	struct sysinfo val;
 
 	if (argc)
@@ -2502,13 +2501,7 @@ static int kdb_summary(int argc, const char **argv)
 	kdb_printf("domainname %s\n", init_uts_ns.name.domainname);
 
 	now = __ktime_get_real_seconds();
-	time64_to_tm(now, 0, &tm);
-	kdb_printf("date       %04ld-%02d-%02d %02d:%02d:%02d "
-		   "tz_minuteswest %d\n",
-		1900+tm.tm_year, tm.tm_mon+1, tm.tm_mday,
-		tm.tm_hour, tm.tm_min, tm.tm_sec,
-		sys_tz.tz_minuteswest);
-
+	kdb_printf("date       %ptTs tz_minuteswest %d\n", &now, sys_tz.tz_minuteswest);
 	kdb_sysinfo(&val);
 	kdb_printf("uptime     ");
 	if (val.uptime > (24*60*60)) {