Fix wrong voice call time in battery page

The voice call is belong to DrainType.PHONE, which is not an app.
This cl stop using method in BatteryUtils to calculate the time, since
that method should only be used for DrainType.APP

Bug: 37402819
Test: RunSettingsRoboTests
Change-Id: I3aa7366401e54df87ffe913af0dcb1bcd5abf110