ASoC: ak4642: Make of_device_id array const

Make of_device_id array const, because all OF functions handle it as const
Signed-off-by: Kiran Padwal <kiran.padwal21@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/codecs/ak4642.c

@@ -547,7 +547,7 @@ static const struct ak4642_drvdata ak4648_drvdata = {
 	.extended_frequencies = 1,
 };
 
-static struct of_device_id ak4642_of_match[];
+static const struct of_device_id ak4642_of_match[];
 static int ak4642_i2c_probe(struct i2c_client *i2c,
 			    const struct i2c_device_id *id)
 {
@@ -593,7 +593,7 @@ static int ak4642_i2c_remove(struct i2c_client *client)
 	return 0;
 }
 
-static struct of_device_id ak4642_of_match[] = {
+static const struct of_device_id ak4642_of_match[] = {
 	{ .compatible = "asahi-kasei,ak4642",	.data = &ak4642_drvdata},
 	{ .compatible = "asahi-kasei,ak4643",	.data = &ak4643_drvdata},
 	{ .compatible = "asahi-kasei,ak4648",	.data = &ak4648_drvdata},