mfd: max8907: 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>
diff --git a/drivers/mfd/max8907.c b/drivers/mfd/max8907.c
index 0774031..232749c 100644
--- a/drivers/mfd/max8907.c
+++ b/drivers/mfd/max8907.c
@@ -305,7 +305,7 @@
 }
 
 #ifdef CONFIG_OF
-static struct of_device_id max8907_of_match[] = {
+static const struct of_device_id max8907_of_match[] = {
 	{ .compatible = "maxim,max8907" },
 	{ },
 };