[ALSA] Fix synchronize_irq() bugs, redundancies

free_irq() calls synchronize_irq() for you, so there is no need for
drivers to manually do the same thing (again).  Thus, calls where
sync-irq immediately precedes free-irq can be simplified.

However, during this audit several bugs were noticed, where free-irq is
preceded by a "irq >= 0" check... but the sync-irq call is not covered
by the same check.

So, where sync-irq could not be eliminated completely, the missing check
was added.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/via82xx.c b/sound/pci/via82xx.c
index a756be6..b585cc3 100644
--- a/sound/pci/via82xx.c
+++ b/sound/pci/via82xx.c
@@ -2236,7 +2236,7 @@
 	/* disable interrupts */
 	for (i = 0; i < chip->num_devs; i++)
 		snd_via82xx_channel_reset(chip, &chip->devs[i]);
-	synchronize_irq(chip->irq);
+
 	if (chip->irq >= 0)
 		free_irq(chip->irq, chip);
  __end_hw: