objecter: remove useless mark_down code
objecter: remove useless mark_down code

We already check sessions a bit further down, and this code only worked
when we got incrementals, not full maps.  Take it out.

Signed-off-by: Sage Weil <6dd34506bbd5e58221bbb3e4732d97c91f02277b@newdream.net>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph