spi: imx: 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>

drivers/spi/spi-imx.c

@@ -674,7 +674,7 @@ static struct spi_imx_devtype_data imx51_ecspi_devtype_data = {
 	.devtype = IMX51_ECSPI,
 };
 
-static struct platform_device_id spi_imx_devtype[] = {
+static const struct platform_device_id spi_imx_devtype[] = {
 	{
 		.name = "imx1-cspi",
 		.driver_data = (kernel_ulong_t) &imx1_cspi_devtype_data,