ALSA: cs46xx: 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/20191210063454.31603-13-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/cs46xx/cs46xx_lib.c

@@ -3989,6 +3989,7 @@ int snd_cs46xx_create(struct snd_card *card,
 		return -EBUSY;
 	}
 	chip->irq = pci->irq;
+	card->sync_irq = chip->irq;
 
 #ifdef CONFIG_SND_CS46XX_NEW_DSP
 	chip->dsp_spos_instance = cs46xx_dsp_spos_create(chip);