ASoC: generic-dmaengine-pcm: use a more common dma name

The examples in Documentation/devicetree/bindings/dma/dma.txt recommends
the name for dma channel doing both RX and TX to be "rx-tx".  This
becomes a common pattern that has been adopted by platforms that
converts to generic DMA bindings.  Let's follow this common pattern in
generic-dmaengine-pcm.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/soc-generic-dmaengine-pcm.c

@@ -227,7 +227,7 @@ static void dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm,
 		return;
 
 	if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX) {
-		pcm->chan[0] = of_dma_request_slave_channel(of_node, "tx_rx");
+		pcm->chan[0] = of_dma_request_slave_channel(of_node, "rx-tx");
 		pcm->chan[1] = pcm->chan[0];
 	} else {
 		for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {