selftests/seccomp: Try to fit runtime of benchmark into timeout

The seccomp benchmark runs five scenarios, one calibration run with no
seccomp filters enabled then four further runs each adding a filter. The
calibration run times itself for 15s and then each additional run executes
for the same number of times.

Currently the seccomp tests, including the benchmark, run with an extended
120s timeout but this is not sufficient to robustly run the tests on a lot
of platforms. Sample timings from some recent runs:

   Platform          Run 1  Run 2  Run 3  Run 4
   ---------         -----  -----  -----  -----
   PowerEdge R200    16.6s  16.6s  31.6s  37.4s
   BBB (arm)         20.4s  20.4s  54.5s
   Synquacer (arm64) 20.7s  23.7s  40.3s

The x86 runs from the PowerEdge are quite marginal and routinely fail, for
the successful run reported here the timed portions of the run are at
117.2s leaving less than 3s of margin which is frequently breached. The
added overhead of adding filters on the other platforms is such that there
is no prospect of their runs fitting into the 120s timeout, especially
on 32 bit arm where there is no BPF JIT.

While we could lower the time we calibrate for I'm also already seeing the
currently completing runs reporting issues with the per filter overheads
not matching expectations:

Let's instead raise the timeout to 180s which is only a 50% increase on the
current timeout which is itself not *too* large given that there's only two
tests in this suite.
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/seccomp/settings

-timeout=120
+timeout=180