Get Vibrator from Context instead of using private API.

Bug: 6334179
Change-Id: I1582daff119a1e7d507f7e3b161710a75971a68e
diff --git a/src/com/android/stk/ToneDialog.java b/src/com/android/stk/ToneDialog.java
index ba4a957..3251aba 100644
--- a/src/com/android/stk/ToneDialog.java
+++ b/src/com/android/stk/ToneDialog.java
@@ -54,7 +54,7 @@
         }
     };
 
-    Vibrator mVibrator = new Vibrator();
+    Vibrator mVibrator = (Vibrator)getSystemService(VIBRATOR_SERVICE);
 
     // Message id to signal tone duration timeout.
     private static final int MSG_ID_STOP_TONE = 0xda;