mfd: max77693: 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: NKrzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: NChanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

drivers/mfd/max77693.c

@@ -243,7 +243,7 @@ static const struct dev_pm_ops max77693_pm = {
 };
 
 #ifdef CONFIG_OF
-static struct of_device_id max77693_dt_match[] = {
+static const struct of_device_id max77693_dt_match[] = {
 	{ .compatible = "maxim,max77693" },
 	{},
 };