regulator: lp3971: Convert to use regulator_map_voltage_ascend

All regulators have ascendant voltage list in this driver.
Thus use regulator_map_voltage_ascend is more efficient than the default
regulator_map_voltage_iterate.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/regulator/lp3971.c

@@ -163,6 +163,7 @@ static int lp3971_ldo_set_voltage_sel(struct regulator_dev *dev,
 
 static struct regulator_ops lp3971_ldo_ops = {
 	.list_voltage = regulator_list_voltage_table,
+	.map_voltage = regulator_map_voltage_ascend,
 	.is_enabled = lp3971_ldo_is_enabled,
 	.enable = lp3971_ldo_enable,
 	.disable = lp3971_ldo_disable,
@@ -236,6 +237,7 @@ static int lp3971_dcdc_set_voltage_sel(struct regulator_dev *dev,
 
 static struct regulator_ops lp3971_dcdc_ops = {
 	.list_voltage = regulator_list_voltage_table,
+	.map_voltage = regulator_map_voltage_ascend,
 	.is_enabled = lp3971_dcdc_is_enabled,
 	.enable = lp3971_dcdc_enable,
 	.disable = lp3971_dcdc_disable,