Toshiba Satellite C870 shows interrupt problems occasionally when
certain mixer controls like "Mic Switch" is toggled.  This seems
worked around by not using MSI.

Bugzilla: https://bugzilla.novell.com/show_bug.cgi?id=833585
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>