Fix Battery usage page refresh issue

restartBatteryStatsLoader made a loader existed in fragment. onStart
will resume the loader. onResume registers mBatteryBroadcastReceiver
will caused the loader activated the second time. We move
restartBatteryStatsLoader to onStart can reduce the loader runs only
once.

Fixes: 140488811
Test: manual
Change-Id: I4cac574ea8e9c07c1a9df48a57fb8140d5687b21