ASoC: Get correct revision id for wm2200

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/codecs/wm2200.c b/sound/soc/codecs/wm2200.c
index a9388df..acbdc5f 100644
--- a/sound/soc/codecs/wm2200.c
+++ b/sound/soc/codecs/wm2200.c
@@ -2084,7 +2084,7 @@
 		goto err_reset;
 	}
 
-	wm2200->rev = ret & WM2200_DEVICE_REVISION_MASK;
+	wm2200->rev = reg & WM2200_DEVICE_REVISION_MASK;
 
 	dev_info(&i2c->dev, "revision %c\n", wm2200->rev + 'A');