drivers/rtc/test: Update driver to address y2038/y2106 issues

drivers/rtc/test: Update driver to address y2038/y2106 issues

This driver has a number of y2038/y2106 issues.

This patch resolves them by:

 - Replacing get_seconds() with ktime_get_real_seconds()
 - Replacing rtc_time_to_tm() with rtc_time64_to_tm()

Also add test_rtc_set_mmss64() for testing rtc_class_ops's
set_mmss64(), which can be activated by "test_mmss64" module
parameter.

Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1427945681-29972-9-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>