selftests/run_kselftest.sh: Fix help string for --per-test-log
This is documented as --per_test_log but the argument is actually
--per-test-log.
Link: https://lore.kernel.org/r/20241220-per-test-log-v1-1-de5afe69fdf4@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
authored by