[PATCH RFT] regulator: max1586: Implement get_voltage_sel callback

This is required since commit f7df20ec32 "regulator: core: Use list_voltage() to read single voltage regulators", otherwise _regulator_get_voltage returns rdev->desc->ops->list_voltage(rdev, 0). The Maxim 1586 controls V3 and V6 voltages, but offers no way of reading back the set up value. Thus

[PATCH RFT] regulator: max1586: Implement get_voltage_sel callback

This is required since commit f7df20ec32 regulator: core: Use list_voltage() to read single voltage regulators, otherwise _regulator_get_voltage returns rdev-desc-ops-list_voltage(rdev, 0). The Maxim 1586 controls V3 and V6 voltages, but offers no way of reading back the set up value. Thus this