ALSA: sonicvibes: 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.

Link: https://lore.kernel.org/r/20191210063454.31603-36-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/sonicvibes.c

@@ -1267,6 +1267,7 @@ static int snd_sonicvibes_create(struct snd_card *card,
 		return -EBUSY;
 	}
 	sonic->irq = pci->irq;
+	card->sync_irq = sonic->irq;
 
 	pci_read_config_dword(pci, 0x40, &dmaa);
 	pci_read_config_dword(pci, 0x48, &dmac);