selftests/timers: Turn off timeout setting

The following 4 tests in timers can take longer than the default 45
seconds that added in commit 852c8cbf34d3 ("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: 852c8cbf34d3 ("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>