performancecontrol: fix layout derp and enabled battery info

There is already a battery_settings.xml in Settings which will
overlay the local one. Renamed the local one to pc_battery_settings.xml.

Also enabled the battery info tab for devices without fast charge

Change-Id: I023cf76a9b73b091ba1e67fd2a84fea1de753db4
Merge pull request #1 from omnirom/android-4.3

performancecontrol: fix layout derp and enabled battery info