regulator: hi6421v600: Use regulator_map_voltage_ascend

All the voltage tables have entries in ascendant order, so use
regulator_map_voltage_ascend to speed up the mapping.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Link: https://lore.kernel.org/r/20210610134128.2477821-1-axel.lin@ingics.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/hi6421v600-regulator.c

@@ -166,7 +166,7 @@ static const struct regulator_ops hi6421_spmi_ldo_rops = {
 	.enable = hi6421_spmi_regulator_enable,
 	.disable = regulator_disable_regmap,
 	.list_voltage = regulator_list_voltage_table,
-	.map_voltage = regulator_map_voltage_iterate,
+	.map_voltage = regulator_map_voltage_ascend,
 	.get_voltage_sel = regulator_get_voltage_sel_regmap,
 	.set_voltage_sel = regulator_set_voltage_sel_regmap,
 	.get_mode = hi6421_spmi_regulator_get_mode,