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/pinctrl-tegra30.c b/drivers/pinctrl/pinctrl-tegra30.c
index fe2d2cf..e7b72e9 100644
--- a/drivers/pinctrl/pinctrl-tegra30.c
+++ b/drivers/pinctrl/pinctrl-tegra30.c
@@ -2484,7 +2484,7 @@
 	return tegra_pinctrl_probe(pdev, &tegra30_pinctrl);
 }
 
-static struct of_device_id tegra30_pinctrl_of_match[] = {
+static const struct of_device_id tegra30_pinctrl_of_match[] = {
 	{ .compatible = "nvidia,tegra30-pinmux", },
 	{ },
 };