Use FooterPreference in xml explicitly

Removed the FooterPreferenceMixin from the SmartBatterySettings page.

Fixes: 139514284
Test: manual test
Change-Id: If9aee92916d02b731bdb71e9c95237e1c3ff7f1d

res/xml/smart_battery_detail.xml

@@ -46,4 +46,9 @@
         android:key="restricted_app"
         android:title="@string/restricted_app_title"/>
 
+    <com.android.settingslib.widget.FooterPreference
+        android:key="smart_battery_detail_footer"
+        android:title="@string/smart_battery_footer"
+        android:selectable="false"
+        settings:searchable="false"/>
 </PreferenceScreen>

src/com/android/settings/fuelgauge/SmartBatterySettings.java

@@ -18,7 +18,6 @@ package com.android.settings.fuelgauge;
 
 import android.app.settings.SettingsEnums;
 import android.content.Context;
-import android.os.Bundle;
 import android.provider.SearchIndexableResource;
 
 import com.android.settings.R;
@@ -40,12 +39,6 @@ import java.util.List;
 public class SmartBatterySettings extends DashboardFragment {
     public static final String TAG = "SmartBatterySettings";
 
-    @Override
-    public void onCreate(Bundle icicle) {
-        super.onCreate(icicle);
-        mFooterPreferenceMixin.createFooterPreference().setTitle(R.string.smart_battery_footer);
-    }
-
     @Override
     public int getMetricsCategory() {
         return SettingsEnums.FUELGAUGE_SMART_BATTERY;