Set default value of battery percent preference

Read config_defaultBatteryPercentageSetting to set default
preference value for battery percentage in SystemUI.

Bug: 189235242
Test: Set resource and check device at boot
Change-Id: I6427a3b76f5641b387dc19f45e17b30820911e3a

src/com/android/settings/display/BatteryPercentagePreferenceController.java

@@ -67,7 +67,9 @@ public class BatteryPercentagePreferenceController extends BasePreferenceControl
     @Override
     public void updateState(Preference preference) {
         int setting = Settings.System.getInt(mContext.getContentResolver(),
-                SHOW_BATTERY_PERCENT, 0);
+                SHOW_BATTERY_PERCENT,
+                mContext.getResources().getBoolean(
+                R.bool.config_defaultBatteryPercentageSetting) ? 1 : 0);
 
         ((SwitchPreference) preference).setChecked(setting == 1);
     }