ALSA: memalloc: Correctly name as WC

SNDRV_DMA_TYPE_DEV_UC and SNDRV_DMA_TYPE_DEV_UC_SG are incorrectly
named as if they were for the uncached memory, while actually we set
the pages as write-combined.  Rename them to reflect the right
attribute.

Acked-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210802072815.13551-3-tiwai@suse.de


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