regulator: tps6586x: 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>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/regulator/tps6586x-regulator.c

@@ -70,6 +70,7 @@ static inline struct device *to_tps6586x_dev(struct regulator_dev *rdev)
 
 static struct regulator_ops tps6586x_regulator_ops = {
 	.list_voltage = regulator_list_voltage_table,
+	.map_voltage = regulator_map_voltage_ascend,
 	.get_voltage_sel = regulator_get_voltage_sel_regmap,
 	.set_voltage_sel = regulator_set_voltage_sel_regmap,