regulator: Set list_voltage callback for 88pm8607

Current code implements pm8607_list_voltage but does not set the list_voltage
callback function in pm8607_regulator_ops. Fix it.
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Tested-by: Jett Zhou <jtzhou@marvell.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/regulator/88pm8607.c

@@ -328,6 +328,7 @@ static int pm8607_is_enabled(struct regulator_dev *rdev)
 }
 
 static struct regulator_ops pm8607_regulator_ops = {
+	.list_voltage	= pm8607_list_voltage,
 	.set_voltage	= pm8607_set_voltage,
 	.get_voltage	= pm8607_get_voltage,
 	.enable		= pm8607_enable,