pinctrl: Make of_device_id array const

Make of_device_id array const, because all OF functions handle it as
const.

Signed-off-by: Kiran Padwal <kiran.padwal21@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/pinctrl/spear/pinctrl-spear1310.c b/drivers/pinctrl/spear/pinctrl-spear1310.c
index 1a8bbfe..6d57d43 100644
--- a/drivers/pinctrl/spear/pinctrl-spear1310.c
+++ b/drivers/pinctrl/spear/pinctrl-spear1310.c
@@ -2692,7 +2692,7 @@
 	.modes_supported = false,
 };
 
-static struct of_device_id spear1310_pinctrl_of_match[] = {
+static const struct of_device_id spear1310_pinctrl_of_match[] = {
 	{
 		.compatible = "st,spear1310-pinmux",
 	},