spi: constify of_device_id array

of_device_id is always used as const.
(See driver.of_match_table and open firmware functions)

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/spi-mpc512x-psc.c b/drivers/spi/spi-mpc512x-psc.c
index ecae0d4..965d2bd 100644
--- a/drivers/spi/spi-mpc512x-psc.c
+++ b/drivers/spi/spi-mpc512x-psc.c
@@ -588,7 +588,7 @@
 	return mpc512x_psc_spi_do_remove(&op->dev);
 }
 
-static struct of_device_id mpc512x_psc_spi_of_match[] = {
+static const struct of_device_id mpc512x_psc_spi_of_match[] = {
 	{ .compatible = "fsl,mpc5121-psc-spi", },
 	{},
 };
diff --git a/drivers/spi/spi-octeon.c b/drivers/spi/spi-octeon.c
index b283d53..e99d6a9 100644
--- a/drivers/spi/spi-octeon.c
+++ b/drivers/spi/spi-octeon.c
@@ -238,7 +238,7 @@
 	return 0;
 }
 
-static struct of_device_id octeon_spi_match[] = {
+static const struct of_device_id octeon_spi_match[] = {
 	{ .compatible = "cavium,octeon-3010-spi", },
 	{},
 };
diff --git a/drivers/spi/spi-st-ssc4.c b/drivers/spi/spi-st-ssc4.c
index 2faeaa7..f17c0ab 100644
--- a/drivers/spi/spi-st-ssc4.c
+++ b/drivers/spi/spi-st-ssc4.c
@@ -482,7 +482,7 @@
 	SET_RUNTIME_PM_OPS(spi_st_runtime_suspend, spi_st_runtime_resume, NULL)
 };
 
-static struct of_device_id stm_spi_match[] = {
+static const struct of_device_id stm_spi_match[] = {
 	{ .compatible = "st,comms-ssc4-spi", },
 	{},
 };