ASoC: rsnd: add DVC support

This patch adds DVC (Digital Volume Controller)
support which is member of CMD unit.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/sound/soc/sh/rcar/src.c b/sound/soc/sh/rcar/src.c
index 035eda2..7da87cd 100644
--- a/sound/soc/sh/rcar/src.c
+++ b/sound/soc/sh/rcar/src.c
@@ -536,12 +536,14 @@
 static int rsnd_src_start_gen2(struct rsnd_mod *mod,
 			       struct rsnd_dai *rdai)
 {
+	struct rsnd_dai_stream *io = rsnd_mod_to_io(mod);
 	struct rsnd_src *src = rsnd_mod_to_src(mod);
+	u32 val = rsnd_io_to_mod_dvc(io) ? 0x01 : 0x11;
 
 	rsnd_dma_start(rsnd_mod_to_dma(&src->mod));
 
 	rsnd_mod_write(mod, SSI_CTRL, 0x1);
-	rsnd_mod_write(mod, SRC_CTRL, 0x11);
+	rsnd_mod_write(mod, SRC_CTRL, val);
 
 	return rsnd_src_start(mod, rdai);
 }