If set link state cmd is present in MC thread and is not processed,
during unload/SSR the msg is discarded but callback arg is not freed.
To fix this free the callback argument while discarding the link state
cmd from WMA msg queue.
Change-Id: Ie532a8983c8efbf3a24eef3b93a8c723bfc65a3f
CRs-Fixed: 2053978