kunit: Fix the wrong err path and add goto labels in kunit_filter_suites()

Take the last kfree(parsed_filters) and add it to be the first. Take
the first kfree(copy) and add it to be the last. The Best practice is to
return these errors reversely.

And as David suggested, add several labels which target only the things
which actually have been allocated so far.

Fixes: 529534e8 ("kunit: Add ability to filter attributes")
Fixes: abbf7381 ("kunit: fix possible memory leak in kunit_filter_suites()")
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Reviewed-by: Rae Moar <rmoar@google.com>
Suggested-by: David Gow <davidgow@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>