ocfs2: fix wake_up in unlock_ast

In ocfs2_unlock_ast(), call wake_up() on lockres before releasing
the spin lock on it.  As soon as the spin lock is released, the
lockres can be freed.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>