regulator: core: Refactor regulator_list_voltage()

Change _regulator_list_voltage() argument from regulator to
regulator_dev in order to provide better separation of core layers.
Allow calling _regulator_list_voltage() from functions, with
regulator_dev argument. This refactoring is needed in order to
implement setting voltage of coupled regulators.
Signed-off-by: Maciej Purski <m.purski@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -2447,10 +2447,9 @@ static int _regulator_is_enabled(struct regulator_dev *rdev)
 	return rdev->desc->ops->is_enabled(rdev);
 }
 
-static int _regulator_list_voltage(struct regulator *regulator,
+static int _regulator_list_voltage(struct regulator_dev *rdev,
 				   unsigned selector, int lock)
 {
-	struct regulator_dev *rdev = regulator->rdev;
 	const struct regulator_ops *ops = rdev->desc->ops;
 	int ret;
 
@@ -2466,7 +2465,8 @@ static int _regulator_list_voltage(struct regulator *regulator,
 		if (lock)
 			mutex_unlock(&rdev->mutex);
 	} else if (rdev->is_switch && rdev->supply) {
-		ret = _regulator_list_voltage(rdev->supply, selector, lock);
+		ret = _regulator_list_voltage(rdev->supply->rdev,
+					      selector, lock);
 	} else {
 		return -EINVAL;
 	}
@@ -2542,7 +2542,7 @@ EXPORT_SYMBOL_GPL(regulator_count_voltages);
  */
 int regulator_list_voltage(struct regulator *regulator, unsigned selector)
 {
-	return _regulator_list_voltage(regulator, selector, 1);
+	return _regulator_list_voltage(regulator->rdev, selector, 1);
 }
 EXPORT_SYMBOL_GPL(regulator_list_voltage);