selftests/futex: Fix futex_cmp_requeue_pi() error handling

An earlier (pre-kernel-integration) refactoring of this code mistakenly
replaced the error condition, <, with a >. Use < to detect an error as
opposed to a successful requeue or signal race.
Reported-by: NDavid Binderman <dcb314@hotmail.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: NDarren Hart <dvhart@linux.intel.com>
Signed-off-by: NShuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/futex/functional/futex_requeue_pi_signal_restart.c

@@ -191,7 +191,7 @@ int main(int argc, char *argv[])
 		if (res > 0) {
 			atomic_set(&requeued, 1);
 			break;
-		} else if (res > 0) {
+		} else if (res < 0) {
 			error("FUTEX_CMP_REQUEUE_PI failed\n", errno);
 			ret = RET_ERROR;
 			break;