ASoC: fsl: 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>

sound/soc/fsl/imx-audmux.c

@@ -184,7 +184,7 @@ static enum imx_audmux_type {
 	IMX31_AUDMUX,
 } audmux_type;
 
-static struct platform_device_id imx_audmux_ids[] = {
+static const struct platform_device_id imx_audmux_ids[] = {
 	{
 		.name = "imx21-audmux",
 		.driver_data = IMX21_AUDMUX,