ASoC: Squash error codes from regmap down to -1 on read

The ASoC code always uses -1 as the error code due to reporting errors in
band with the value. Ensure we don't confuse anything by making sure we
don't pass actual error codes back into the rest of the code on read.
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/soc-io.c

@@ -55,7 +55,7 @@ static unsigned int hw_read(struct snd_soc_codec *codec, unsigned int reg)
 		if (ret == 0)
 			return val;
 		else
-			return ret;
+			return -1;
 	}
 
 	ret = snd_soc_cache_read(codec, reg, &val);