ALSA: intel8x0: Use the new non-cached allocation for 440MX workaround

intel8x0 driver requires the non-cached pages for 440MX workaround,
and this can be implemented more easily with the new memalloc type,
SNDRV_DMA_TYPE_DEV_UC.  This allows us to reduce lots of code.

Signed-off-by: Takashi Iwai <tiwai@suse.de>