ALSA: hda - Enable snoop bit for AMD controllers

ALSA: hda - Enable snoop bit for AMD controllers

BugLink: http://bugs.launchpad.net/bugs/741825

AMD Hudson controllers give noisy outputs when the buffer data is
rewritten on the fly as PulseAudio does.  This seems fixed by the
snoop bit enabled just like ATI chipset.

Also, disable 64bit DMA as now, to be sure.
We can revisit this later.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
(cherry picked from commit 20c304ed84e05a91b2acae36d428d621d3c1d1c6)
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>