spi: pxa2xx: Constify ACPI device ids

Constify the ACPI device ID array, it doesn't need to be writable at
runtime.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-pxa2xx.c

@@ -1265,7 +1265,7 @@ static void cleanup(struct spi_device *spi)
 
 #ifdef CONFIG_ACPI
 
-static struct acpi_device_id pxa2xx_spi_acpi_match[] = {
+static const struct acpi_device_id pxa2xx_spi_acpi_match[] = {
 	{ "INT33C0", LPSS_LPT_SSP },
 	{ "INT33C1", LPSS_LPT_SSP },
 	{ "INT3430", LPSS_LPT_SSP },