regulator: lp8752: add set_voltage_time_sel func

support delay time in microseconds required to
rise or fall to this new voltage

Change-Id: I1f7c77356e650b9ff01ad0e63fd384e25f774eac
Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>

Author: Elaine Zhang

drivers/regulator/lp8752.c

@@ -117,6 +117,7 @@ static struct regulator_ops lp8752_buck_ops = {
 	.list_voltage = regulator_list_voltage_linear_range,
 	.set_voltage_sel = regulator_set_voltage_sel_regmap,
 	.get_voltage_sel = regulator_get_voltage_sel_regmap,
+	.set_voltage_time_sel = regulator_set_voltage_time_sel,
 	.enable = regulator_enable_regmap,
 	.disable = regulator_disable_regmap,
 	.is_enabled = regulator_is_enabled_regmap,