ALSA: memalloc: Remove a stale comment

The comment about the reused vmalloc helpers is no longer valid after
the recent change for the noncontig allocator.  Drop the stale
comment.

Fixes: ad4f93ca ("ALSA: memalloc: Use proper SG helpers for noncontig allocations")
Link: https://lore.kernel.org/r/20211110063100.21359-1-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/memalloc.c

@@ -615,7 +615,6 @@ static const struct snd_malloc_ops snd_dma_noncontig_ops = {
 	.free = snd_dma_noncontig_free,
 	.mmap = snd_dma_noncontig_mmap,
 	.sync = snd_dma_noncontig_sync,
-	/* re-use vmalloc helpers for get_* ops */
 	.get_addr = snd_dma_noncontig_get_addr,
 	.get_page = snd_dma_noncontig_get_page,
 	.get_chunk_size = snd_dma_noncontig_get_chunk_size,