ALSA: Replace snd_malloc_pages() and snd_free_pages() with standard helpers, take#2

snd_malloc_pages() and snd_free_pages() are merely thin wrappers of
the standard page allocator / free functions.  Even the arguments are
compatible with some standard helpers, so there is little merit of
keeping these wrappers.

This patch replaces the all existing callers of snd_malloc_pages() and
snd_free_pages() with the direct calls of the standard helper
functions.  In this version, we use a recently introduced one,
alloc_pages_exact(), which suits better than the old
snd_malloc_pages() implementation for our purposes.  Then we can avoid
the waste of pages by alignment to power-of-two.

Since alloc_pages_exact() does split pages, we need no longer
__GFP_COMP flag; or better to say, we must not pass __GFP_COMP to
alloc_pages_exact().  So the former unconditional addition of
__GFP_COMP flag in snd_malloc_pages() is dropped, as well as in most
other places.

Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/memalloc.h

@@ -151,9 +151,5 @@ int snd_dma_alloc_pages_fallback(int type, struct device *dev, size_t size,
                                  struct snd_dma_buffer *dmab);
 void snd_dma_free_pages(struct snd_dma_buffer *dmab);
 
-/* basic memory allocation functions */
-void *snd_malloc_pages(size_t size, gfp_t gfp_flags);
-void snd_free_pages(void *ptr, size_t size);
-
 #endif /* __SOUND_MEMALLOC_H */