ASoC: io: Don't dereference regmap if we failed to get one

Avoids a crash in invalid configurations.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>

sound/soc/soc-io.c

@@ -145,10 +145,13 @@ int snd_soc_codec_set_cache_io(struct snd_soc_codec *codec,
 		if (!codec->control_data)
 			codec->control_data = dev_get_regmap(codec->dev, NULL);
 
+		if (codec->control_data) {
 			ret = regmap_get_val_bytes(codec->control_data);
-		/* Errors are legitimate for non-integer byte multiples */
+			/* Errors are legitimate for non-integer byte
+			 * multiples */
 			if (ret > 0)
 				codec->val_bytes = ret;
+		}
 		break;
 
 	default: