pwm: pca9685: 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: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-pca9685.c

@@ -202,7 +202,7 @@ static const struct pwm_ops pca9685_pwm_ops = {
 	.owner = THIS_MODULE,
 };
 
-static struct regmap_config pca9685_regmap_i2c_config = {
+static const struct regmap_config pca9685_regmap_i2c_config = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.max_register = PCA9685_NUMREGS,