ASoC: kirkwood-dma: fix use of virt_to_phys()

This is part of a patch found in Rabeeh Khoury's git tree for the
cubox.

You can not use virt_to_phys() on the address returned from
dma_alloc_coherent(); it may not be part of the kernel direct-mapped
memory.  Fix this to use the DMA address instead.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/kirkwood/kirkwood-dma.c

@@ -178,7 +178,7 @@ static int kirkwood_dma_open(struct snd_pcm_substream *substream)
 	}
 
 	dram = mv_mbus_dram_info();
-	addr = virt_to_phys(substream->dma_buffer.area);
+	addr = substream->dma_buffer.addr;
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		prdata->play_stream = substream;
 		kirkwood_dma_conf_mbus_windows(priv->io,