[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/atiixp_modem.c b/sound/pci/atiixp_modem.c
index a67a869..d457a32 100644
--- a/sound/pci/atiixp_modem.c
+++ b/sound/pci/atiixp_modem.c
@@ -1197,7 +1197,7 @@
 	if (chip->irq < 0)
 		goto __hw_end;
 	snd_atiixp_chip_stop(chip);
-	synchronize_irq(chip->irq);
+
       __hw_end:
 	if (chip->irq >= 0)
 		free_irq(chip->irq, chip);