Unregister hotspot receiver in TetherService.

- when the service exits, also unregister the hotspot receiver.
- move TetherService and HotspotOffReceiver to wifi.tether package.

Change-Id: I0044a52bf80a5530a58b5186ab056de55e83532b
Fixes: 69844871
Test: make RunSettingsRoboTests

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

@@ -1,5 +1,5 @@
 
-package com.android.settings;
+package com.android.settings.wifi.tether;
 
 import android.content.BroadcastReceiver;
 import android.content.Context;

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

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.settings;
+package com.android.settings.wifi.tether;
 
 import android.app.Activity;
 import android.app.AlarmManager;
@@ -167,11 +167,16 @@ public class TetherService extends Service {
         SharedPreferences prefs = getSharedPreferences(PREFS, MODE_PRIVATE);
         prefs.edit().putString(KEY_TETHERS, tethersToString(mCurrentTethers)).commit();
 
+        unregisterReceivers();
         if (DEBUG) Log.d(TAG, "Destroying TetherService");
-        unregisterReceiver(mReceiver);
         super.onDestroy();
     }
 
+    private void unregisterReceivers() {
+        unregisterReceiver(mReceiver);
+        mHotspotReceiver.unregister();
+    }
+
     private void removeTypeAtIndex(int index) {
         mCurrentTethers.remove(index);
         // If we are currently in the middle of a check, we may need to adjust the