Fixed handling of usb state during adb changes.

When changing state to adb from mtp (charging), we want to disable
the old mtp function. Similarly when change to away from adb to
charging, enable the mtp function.

Also the mtp function should never be persisted.

Bug: 31818377
Bug: 31814300
Test: Manually verify that the correct usb configuration is displayed.
Test: Manually verify that logcat is not kicked during boot.
Change-Id: Idcb7f53be39ea38712d5de45b323d8daeb552129