ASoC: ak4554: constify of_device_id array

of_device_id is always used as const.
(See driver.of_match_table and open firmware functions)

Signed-off-by: Fabian Frederick <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/codecs/ak4554.c

···
 	return 0;
 }
 
-static struct of_device_id ak4554_of_match[] = {
+static const struct of_device_id ak4554_of_match[] = {
 	{ .compatible = "asahi-kasei,ak4554" },
 	{},
 };