rgw: fix get cors, delete cors

Remove a couple of variables that overrode class member. Not
really clear how it was working before, might have been a bad
merge / rebase.

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>
Merge pull request #576 from ceph/wip-6078-2

rgw: fix get cors, delete cors

Reviewed-by: Sage Weil <sage@inktank.com>