mfd: pcf50633: 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: NKrzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

drivers/mfd/pcf50633-core.c

@@ -183,7 +183,7 @@ static int pcf50633_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(pcf50633_pm, pcf50633_suspend, pcf50633_resume);
 
-static struct regmap_config pcf50633_regmap_config = {
+static const struct regmap_config pcf50633_regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 8,
 };