ALSA: vx: Convert to the common vmalloc memalloc
The recent change (*) in the ALSA memalloc core allows us to drop the
special vmalloc-specific allocation and page handling. This patch
coverts to the common code.
(*)
1fe7f397cfe2: ALSA: memalloc: Add vmalloc buffer allocation
support
7e8edae39fd1: ALSA: pcm: Handle special page mapping in the
default mmap handler
Since the driver requires the DMA32 allocation, it passes the
specially encoded device to snd_pcm_lib_preallocate_pages().
Link: https://lore.kernel.org/r/20191105151856.10785-16-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>