kselftests: timers: Ease alarmtimer-suspend unreasonable latency value

On the hardware I have, resume latency from an alarm is often
2-3 seconds (with a fair amount of variability due to the RTC's
single second granularity). Having four seconds be the pass/fail
bar is maybe a little too tight, so extend this to 5 seconds.

Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>