Fix bug #15335840 "Safety information" search suggestion shown though

..."Safety information" setting is not available in settings app

- implement a SearchIndexProvider for DeviceInfoSettings and
remove some Preference indexing depending on the device state
and configuration
- remove old non used Preferences
- some code cleaning

Change-Id: I3b2c9dc7cb9f1137b553fed9330aeea4020bd2f8

src/com/android/settings/search/SearchIndexableResources.java

@@ -219,7 +219,7 @@ public final class SearchIndexableResources {
         sResMap.put(DeviceInfoSettings.class.getName(),
                 new SearchIndexableResource(
                         Ranking.getRankForClassName(DeviceInfoSettings.class.getName()),
-                        R.xml.device_info_settings,
+                        NO_DATA_RES_ID,
                         DeviceInfoSettings.class.getName(),
                         R.drawable.ic_settings_about));
     }