Added unregisterReceiver() to avoid leaked IntentReceiver.

Bug: 22202062
Change-Id: Ie55847844eed414df5ecb1fc63d62cb75f17cb1c
diff --git a/src/com/android/phone/MobileNetworkSettings.java b/src/com/android/phone/MobileNetworkSettings.java
index 96d00ae..bcb627e 100644
--- a/src/com/android/phone/MobileNetworkSettings.java
+++ b/src/com/android/phone/MobileNetworkSettings.java
@@ -470,6 +470,12 @@
     }
 
     @Override
+    protected void onDestroy() {
+        super.onDestroy();
+        unregisterReceiver(mPhoneChangeReceiver);
+    }
+
+    @Override
     protected void onResume() {
         super.onResume();
         if (DBG) log("onResume:+");