ASoC: Declare 2 channels for WM8974

The device is a mono device but it can read two channel data and
many I2S controllers only understand 2 channels.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/codecs/wm8974.c b/sound/soc/codecs/wm8974.c
index c5d47bc..207fe3f 100644
--- a/sound/soc/codecs/wm8974.c
+++ b/sound/soc/codecs/wm8974.c
@@ -582,13 +582,13 @@
 	.playback = {
 		.stream_name = "Playback",
 		.channels_min = 1,
-		.channels_max = 1,
+		.channels_max = 2,   /* Only 1 channel of data */
 		.rates = WM8974_RATES,
 		.formats = WM8974_FORMATS,},
 	.capture = {
 		.stream_name = "Capture",
 		.channels_min = 1,
-		.channels_max = 1,
+		.channels_max = 2,   /* Only 1 channel of data */
 		.rates = WM8974_RATES,
 		.formats = WM8974_FORMATS,},
 	.ops = &wm8974_ops,