ASoC: au1x: Constify platform_device_id

The platform_device_id is not modified by the driver and core uses it as
const.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/sound/soc/au1x/db1200.c b/sound/soc/au1x/db1200.c
index c75995f..58c3164 100644
--- a/sound/soc/au1x/db1200.c
+++ b/sound/soc/au1x/db1200.c
@@ -21,7 +21,7 @@
 #include "../codecs/wm8731.h"
 #include "psc.h"
 
-static struct platform_device_id db1200_pids[] = {
+static const struct platform_device_id db1200_pids[] = {
 	{
 		.name		= "db1200-ac97",
 		.driver_data	= 0,