pipeline: update pipeline idle task

The idle tasks scheduler new feature enable idle
tasks to reenter themselves at some later time.
Therefore pipeline tasks needs to be updated
accordingly.

Signed-off-by: Marcin Rajwa <marcin.rajwa@linux.intel.com>

src/audio/pipeline.c

@@ -974,5 +974,5 @@ static uint64_t pipeline_task(void *arg)
 	}
 
 	tracev_pipe("pipeline_task() sched");
-	return p->ipc_pipe.period;
+	return pipeline_is_timer_driven(p) ? p->ipc_pipe.period : 0;
 }