ASoC: kirkwood: 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/kirkwood/kirkwood-i2s.c

@@ -643,7 +643,7 @@ static int kirkwood_i2s_dev_remove(struct platform_device *pdev)
 }
 
 #ifdef CONFIG_OF
-static struct of_device_id mvebu_audio_of_match[] = {
+static const struct of_device_id mvebu_audio_of_match[] = {
 	{ .compatible = "marvell,kirkwood-audio" },
 	{ .compatible = "marvell,dove-audio" },
 	{ .compatible = "marvell,armada370-audio" },