mfd: max77686: Make of_device_id array const

Array of struct of_device_id may be be const as expected by
of_match_table field.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/max77686.c

@@ -47,7 +47,7 @@ static struct regmap_config max77686_regmap_config = {
 };
 
 #ifdef CONFIG_OF
-static struct of_device_id max77686_pmic_dt_match[] = {
+static const struct of_device_id max77686_pmic_dt_match[] = {
 	{.compatible = "maxim,max77686", .data = NULL},
 	{},
 };