ALSA: wavefront: 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/20191210063454.31603-48-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/isa/wavefront/wavefront.c

@@ -409,6 +409,7 @@ snd_wavefront_probe (struct snd_card *card, int dev)
 	}
 	
 	acard->wavefront.irq = ics2115_irq[dev];
+	card->sync_irq = acard->wavefront.irq;
 	acard->wavefront.base = ics2115_port[dev];
 
 	wavefront_synth = snd_wavefront_new_synth(card, hw_dev, acard);