gpio: 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 <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpio-mxc.c

···
 #define GPIO_INT_FALL_EDGE	(mxc_gpio_hwdata->fall_edge)
 #define GPIO_INT_BOTH_EDGES	0x4
 
-static struct platform_device_id mxc_gpio_devtype[] = {
+static const struct platform_device_id mxc_gpio_devtype[] = {
 	{
 		.name = "imx1-gpio",
 		.driver_data = IMX1_GPIO,

drivers/gpio/gpio-mxs.c

···
 	return !(dir & mask);
 }
 
-static struct platform_device_id mxs_gpio_ids[] = {
+static const struct platform_device_id mxs_gpio_ids[] = {
 	{
 		.name = "imx23-gpio",
 		.driver_data = IMX23_GPIO,

drivers/gpio/gpio-ts5500.c

···
 	return 0;
 }
 
-static struct platform_device_id ts5500_dio_ids[] = {
+static const struct platform_device_id ts5500_dio_ids[] = {
 	{ "ts5500-dio1", TS5500_DIO1 },
 	{ "ts5500-dio2", TS5500_DIO2 },
 	{ "ts5500-dio-lcd", TS5500_LCD },