sound/soc/pxa/mmp-pcm.c: use gen_pool_dma_alloc() to allocate dma buffer

Since gen_pool_dma_alloc() is introduced, we implement it to simplify code.
Signed-off-by: Nicolin Chen <b42378@freescale.com>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sound/soc/pxa/mmp-pcm.c

@@ -201,10 +201,9 @@ static int mmp_pcm_preallocate_dma_buffer(struct snd_pcm_substream *substream,
 	if (!gpool)
 		return -ENOMEM;
 
-	buf->area = (unsigned char *)gen_pool_alloc(gpool, size);
+	buf->area = gen_pool_dma_alloc(gpool, size, &buf->addr);
 	if (!buf->area)
 		return -ENOMEM;
-	buf->addr = gen_pool_virt_to_phys(gpool, (unsigned long)buf->area);
 	buf->bytes = size;
 	return 0;
 }