ALSA: cs5535audio: Support PCM sync_stop

The driver invokes snd_pcm_period_elapsed() simply from the interrupt
handler.  Set card->sync_irq for enabling the missing sync_stop PCM
operation, as well as removing the superfluous synchronize_irq()
call.

Link: https://lore.kernel.org/r/20191210063454.31603-14-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/cs5535audio/cs5535audio.c

@@ -237,7 +237,6 @@ static irqreturn_t snd_cs5535audio_interrupt(int irq, void *dev_id)
 
 static int snd_cs5535audio_free(struct cs5535audio *cs5535au)
 {
-	synchronize_irq(cs5535au->irq);
 	pci_set_power_state(cs5535au->pci, PCI_D3hot);
 
 	if (cs5535au->irq >= 0)
@@ -303,6 +302,7 @@ static int snd_cs5535audio_create(struct snd_card *card,
 	}
 
 	cs5535au->irq = pci->irq;
+	card->sync_irq = cs5535au->irq;
 	pci_set_master(pci);
 
 	if ((err = snd_device_new(card, SNDRV_DEV_LOWLEVEL,