selftests/timers: Turn off timeout setting

The following 4 tests in timers can take longer than the default 45
seconds that added in commit 852c8cbf ("selftests/kselftest/runner.sh:
Add 45 second timeout per test") to run:
  * nsleep-lat - 2m7.350s
  * set-timer-lat - 2m0.66s
  * inconsistency-check - 1m45.074s
  * raw_skew - 2m0.013s

Thus they will be marked as failed with the current 45s setting:
  not ok 3 selftests: timers: nsleep-lat # TIMEOUT
  not ok 4 selftests: timers: set-timer-lat # TIMEOUT
  not ok 6 selftests: timers: inconsistency-check # TIMEOUT
  not ok 7 selftests: timers: raw_skew # TIMEOUT

Disable the timeout setting for timers can make these tests finish
properly:
  ok 3 selftests: timers: nsleep-lat
  ok 4 selftests: timers: set-timer-lat
  ok 6 selftests: timers: inconsistency-check
  ok 7 selftests: timers: raw_skew

https://bugs.launchpad.net/bugs/1864626


Fixes: 852c8cbf ("selftests/kselftest/runner.sh: Add 45 second timeout per test")
Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>