Fixes https://bugtrack.alsa-project.org/alsa-bug/view.php?id=4121

Taken from https://bugzilla.redhat.com/show_bug.cgi?id=498060Signed-off-by: NAdam Williamson <awilliam@redhat.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>