Fix Tethering Notifications for multiple ifaces

Used to see multiple notifications if usb tethering and wifi tethering were both used.

bug:2527862
Change-Id: Idc6299c0a70564dd7c8d8d7fe13bde83723134ae
diff --git a/services/java/com/android/server/connectivity/Tethering.java b/services/java/com/android/server/connectivity/Tethering.java
index fcb39c9..d57457eb 100644
--- a/services/java/com/android/server/connectivity/Tethering.java
+++ b/services/java/com/android/server/connectivity/Tethering.java
@@ -365,6 +365,13 @@
             return;
         }
 
+        if (mTetheredNotification != null) {
+            if (mTetheredNotification.icon == icon) {
+                return;
+            }
+            notificationManager.cancel(mTetheredNotification.icon);
+        }
+
         Intent intent = new Intent();
         intent.setClassName("com.android.settings", "com.android.settings.TetherSettings");
         intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);