selftests: futex: print testcase-name and PASS/FAIL/ERROR status

Most of the tests under selftests follow a pattern for their results,
which can then be parsed easily by other external tools easily. Though
futex tests do print the test results very well, it doesn't really
follow the general selftests pattern.

This patch makes necessary changes to fix that.

Output before this patch:
futex_requeue_pi: Test requeue functionality
        Arguments: broadcast=0 locked=0 owner=0 timeout=0ns
Result:  PASS

Output after this patch:
futex_requeue_pi: Test requeue functionality
        Arguments: broadcast=0 locked=0 owner=0 timeout=0ns
selftests: futex-requeue-pi [PASS]

Signed-off-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>