ioping: avoid zero usleep

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>

ioping.c

@@ -615,6 +615,7 @@ int main (int argc, char **argv)
 		if (deadline && now() + interval >= deadline)
 			break;
 
+		if (interval)
 			usleep(interval);
 	}