fix target location for ceilometermiddleware data

this patch corrects I22f929949e3deeb90d14ddad81ccfce9c9de185c.
previous patch incorrectly did not take into account the fact that
ceilometer's api flattens metadata on response.

Change-Id: Iaefd386f7209ee6b8d8c4db5d014aa63cb9f9248
1 file changed