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 <fabf@skynet.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/ak4554.c

@@ -84,7 +84,7 @@ static int ak4554_soc_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static struct of_device_id ak4554_of_match[] = {
+static const struct of_device_id ak4554_of_match[] = {
 	{ .compatible = "asahi-kasei,ak4554" },
 	{},
 };