regulator: 88pm8607: Update update_bit for BUCK2 in pm8607_set_voltage_sel

BUCK2 has the update_bit setting, but current code does not set update_bit
in pm8607_set_voltage_sel.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/regulator/88pm8607.c

@@ -236,6 +236,7 @@ static int pm8607_set_voltage_sel(struct regulator_dev *rdev, unsigned selector)
 		return ret;
 	switch (info->desc.id) {
 	case PM8607_ID_BUCK1:
+	case PM8607_ID_BUCK2:
 	case PM8607_ID_BUCK3:
 		ret = pm860x_set_bits(info->i2c, info->update_reg,
 				      1 << info->update_bit,