rtc: mxc: 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: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-mxc.c

@@ -84,7 +84,7 @@ struct rtc_plat_data {
 	enum imx_rtc_type devtype;
 };
 
-static struct platform_device_id imx_rtc_devtype[] = {
+static const struct platform_device_id imx_rtc_devtype[] = {
 	{
 		.name = "imx1-rtc",
 		.driver_data = IMX1_RTC,