[Wi-Fi] Fix Wi-Fi broken tests

Bug: 150910070
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=com.android.settings.wifi
Change-Id: Ie9b9384610857e2999fe4642a93c2d31ce3315f3

src/com/android/settings/wifi/tether/WifiTetherSwitchBarController.java

@@ -94,7 +94,7 @@ public class WifiTetherSwitchBarController implements
 
     @Override
     public void onClick(View v) {
-        if (mSwitch.isChecked()) {
+        if (((Switch) v).isChecked()) {
             startTether();
         } else {
             stopTether();