kselftests: timers: Increase delay between suspends in alarmtimer-suspend

When testing on some hardware, waiting only a second before
re-triggering suspend can keep TCP connections from re-establishing
which after a number of cycles can cause TCP connections to close
while the test is running.

So extend the delay between suspend calls to 3 seconds to let
the connections stay alive.

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>