rtla: Fix buffer overflow in actions_parse

Currently, tests 3 and 13-22 in tests/timerlat.t fail with error:

    *** buffer overflow detected ***: terminated
    timeout: the monitored command dumped core

The result of running `sudo make check` is

    tests/timerlat.t (Wstat: 0 Tests: 22 Failed: 11)
      Failed tests:  3, 13-22
    Files=3, Tests=34, 140 wallclock secs ( 0.07 usr  0.01 sys + 27.63 cusr
    27.96 csys = 55.67 CPU)
    Result: FAIL

Fix buffer overflow in actions_parse to avoid this error. After this
change, the tests results are

    tests/hwnoise.t ... ok
    tests/osnoise.t ... ok
    tests/timerlat.t .. ok
    All tests successful.
    Files=3, Tests=34, 186 wallclock secs ( 0.06 usr  0.01 sys + 41.10 cusr
    44.38 csys = 85.55 CPU)
    Result: PASS

Link: https://lore.kernel.org/164ffc2ec8edacaf1295789dad82a07817b6263d.1757034919.git.ipravdin.official@gmail.com


Fixes: 6ea082b1 ("rtla/timerlat: Add action on threshold feature")
Signed-off-by: Ivan Pravdin <ipravdin.official@gmail.com>
Reviewed-by: Tomas Glozar <tglozar@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>