Revert "[Settings] Support getSystemService(Class<T>)"

This reverts commit d5ccde31a8.

Reason for revert: failure on test cases

Change-Id: I0a179a6ebb5ef1dec566ce6e8facd5f3b82d7c8a

src/com/android/settings/wifi/WifiNoInternetDialog.java

@@ -107,7 +107,7 @@ public class WifiNoInternetDialog extends AlertActivity implements
             }
         };
 
-        mCM = getSystemService(ConnectivityManager.class);
+        mCM = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
         mCM.registerNetworkCallback(request, mNetworkCallback);
 
         final NetworkInfo ni = mCM.getNetworkInfo(mNetwork);