Use the new isNetworkSupported api for wifi-only

Didn't have an API for this before so people used a hacked system property (ro.carrier)
to determine if the device supported mobile data.  Added new API and switching callsites.

bug:5087537
Change-Id: Ibd799559be102a9e2fd552d1a23d1afbcf8f4614

src/com/android/settings/LocationSettings.java

@@ -101,7 +101,7 @@ public class LocationSettings extends SettingsPreferenceFragment
         }
 
         // Change the summary for wifi-only devices
-        if (Utils.isWifiOnly()) {
+        if (Utils.isWifiOnly(getActivity())) {
             mNetwork.setSummaryOn(R.string.location_neighborhood_level_wifi);
         }