ASoC: wm8940: Fix check on error code form snd_soc_codec_set_cache_io

Fix for typo in commit 8d50e447
ASoC: Factor out I/O for Wolfson 8 bit data 16 bit register CODECs
Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/codecs/wm8940.c

@@ -790,7 +790,7 @@ static int wm8940_register(struct wm8940_priv *wm8940,
 	codec->reg_cache = &wm8940->reg_cache;
 
 	ret = snd_soc_codec_set_cache_io(codec, 8, 16, control);
-	if (ret == 0) {
+	if (ret < 0) {
 		dev_err(codec->dev, "Failed to set cache I/O: %d\n", ret);
 		return ret;
 	}