Directly use BaseIndexableProvider

- Add function getXmlResourceId, Fragments don't need to write
xml resource id twice.
- Remove getPreferenceControllers from Indexable.java. Because it will
move to SettingsLib later for other apps which don't need this function

Bug: 135053028
Test: robolectric
Change-Id: I1e74519aecdea3dde64a5aea79f08d766dbc0003

src/com/android/settings/deviceinfo/firmwareversion/FirmwareVersionSettings.java

@@ -47,6 +47,6 @@ public class FirmwareVersionSettings extends DashboardFragment {
         return SettingsEnums.DIALOG_FIRMWARE_VERSION;
     }
 
-    public static final Indexable.SearchIndexProvider SEARCH_INDEX_DATA_PROVIDER =
+    public static final BaseSearchIndexProvider SEARCH_INDEX_DATA_PROVIDER =
             new BaseSearchIndexProvider(R.xml.firmware_version);
 }