Currently at TSO segment free it's debug information is not
cleared. TSO segment TX descriptor owner is part of the debug
information. As a result even after segment free still its
point to stale TX descriptor as it's owner. In this change at
TSO segment free set TX desc owner to NULL.
Change-Id: I09f927d78c7b3aa4691aa69acbd4cef5002cf11d
CRs-Fixed: 2063433