For devices which don't support dreaming on battery, we can offer
simpler options since the device must always be charging for
screensavers to appear. Therefore there are only two options:
1. While charging
2. While docked and charging
Test: flashed and verified on device
Test: make -j64 RunSettingsRoboTests
Fixes: 226187572
Change-Id: I6ed24cda8874f2fb941f6cfded9ed97ed78a3cb6