ALSA: memalloc: Use proper DMA mapping API for x86 WC buffer allocations

The x86 WC page allocation assumes incorrectly the DMA address
directly taken from the page.  Also it checks the DMA ops
inappropriately for switching to the own method.

This patch rewrites the stuff to use the proper DMA mapping API
instead.

Link: https://patch.msgid.link/20240912155227.4078-2-tiwai@suse.de


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