ALSA: usb-audio: stop both data and sync endpoints asynchronously

As we are stopping the endpoints asynchronously now, it's better to
trigger the stop of both data and sync endpoints and wait for pending
stopping operations, instead of the sequential trigger-and-wait
procedure.

So the wait argument in snd_usb_endpoint_stop() is dropped, and it's
expected that the caller synchronizes explicitly by calling
snd_usb_endpoint_sync_pending_stop().  (Actually there is only one
place calling this, so it was safe to change.)

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index d90604a..4750d3d 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -266,10 +266,15 @@
 static void stop_endpoints(struct snd_usb_substream *subs, bool wait)
 {
 	if (test_and_clear_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags))
-		snd_usb_endpoint_stop(subs->sync_endpoint, wait);
+		snd_usb_endpoint_stop(subs->sync_endpoint);
 
 	if (test_and_clear_bit(SUBSTREAM_FLAG_DATA_EP_STARTED, &subs->flags))
-		snd_usb_endpoint_stop(subs->data_endpoint, wait);
+		snd_usb_endpoint_stop(subs->data_endpoint);
+
+	if (wait) {
+		snd_usb_endpoint_sync_pending_stop(subs->sync_endpoint);
+		snd_usb_endpoint_sync_pending_stop(subs->data_endpoint);
+	}
 }
 
 static int deactivate_endpoints(struct snd_usb_substream *subs)