PM: Switch to use %ptR

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

Cc: linux-pm@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>