Set reason code when disconnecting

Possible fix for https://code.google.com/p/android/issues/detail?id=152085

There is a bug identified in Android NetworkInfo API
(http://developer.android.com/reference/android/net/NetworkInfo.html)
since Android Lollipop 5.0.0 release. On Android 4.4 and prior, the
NetworkInfo API was correctly reporting disconnection reason. In
Android 5.0+, this NetworkInfo API does not correctly report the
reason of disconnection.

The submitted framework modification appears to fix this issue
and report the reason.

Change-Id: I4b43cf99983b2b369503c9484302972e3d0b2330