kselftests: timers: Reduce default runtime on inconsistency-check and set-timer-lat

For the default run_timers target, the timers tests takes the
majority of kselftests runtime.

So this patch reduces the default runtime for inconsistentcy-check
and set-timer-lat, which reduced the runtime almost in half.

Before:	11m48.629s
After:	6m47.723s

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>