commit d70a1b98 upstream.

The Arcam rPAC seems to have the same problem - whenever anything
(alsamixer, udevd, 3.9+ kernel from 60af3d03, ..) attempts to
access mixer / control interface of the card, the firmware "locks up"
the entire device, resulting in
  SNDRV_PCM_IOCTL_HW_PARAMS failed (-5): Input/output error
from alsa-lib.

Other operating systems can somehow read the mixer (there seems to be
playback volume/mute), but any manipulation is ignored by the device
(which has hardware volume controls).
Signed-off-by: Jiri Jaburek <jjaburek@redhat.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>