mfd: tps6586x: Make of_device_id array const

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

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/tps6586x.c b/drivers/mfd/tps6586x.c
index 835e554..8e1dbc4 100644
--- a/drivers/mfd/tps6586x.c
+++ b/drivers/mfd/tps6586x.c
@@ -444,7 +444,7 @@
 	return pdata;
 }
 
-static struct of_device_id tps6586x_of_match[] = {
+static const struct of_device_id tps6586x_of_match[] = {
 	{ .compatible = "ti,tps6586x", },
 	{ },
 };