mfd: da9150: Constify struct regmap_config

The regmap_config struct may be const because it is not modified by the
driver and regmap_init() accepts pointer to const.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/da9150-core.c

@@ -95,7 +95,7 @@ static const struct regmap_range_cfg da9150_range_cfg[] = {
 	},
 };
 
-static struct regmap_config da9150_regmap_config = {
+static const struct regmap_config da9150_regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.ranges = da9150_range_cfg,