oeqa/runtime/stap: fix script logic problem

oeqa/runtime/stap: fix script logic problem

Looks as a typo introduced by "6cf4d23a2d26c2767edd93f2eb317ff759b5a992
(oeqa/runtime/stap: improve systemtap test)" - when original command was
split into two parts 'self.target.run' was missed for the second part.

Note this and previos commit issues were masked because mentioned
commit has try/except around tests, so failures that normally are
reported when test assertEqual throw an exception never reached oeqa
infra.

Effectively, this test was broken for the last 3 years. I will leave
blanket try/except around test for now, so this test will pass all
the time as long as dmesg is working. But at least with the fixes
one can inspect log.do_testimage output and check that all steps
are successful or not.

Signed-off-by: Victor Kamensky <victor.kamensky7@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>