[ALSA] remove incorrect usage of SNDRV_PCM_INFO_SYNC_START and snd_pcm_set_sync()

Set the SNDRV_PCM_INFO_SYNC_START flag and the substream's sync ID
(only) if the substream actually can be linked to another one.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

sound/pci/nm256/nm256.c

@@ -842,7 +842,6 @@ static void snd_nm256_setup_stream(struct nm256 *chip, struct nm256_stream *s,
 	runtime->private_data = s;
 	s->substream = substream;
 
-	snd_pcm_set_sync(substream);
 	snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
 				   &constraints_rates);
 }