rgw: call throttle_data() even if renew_state() failed

Otherwise we're going to leak the aio callback handle.

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
Merge pull request #2257 from ceph/wip-8784

rgw: call throttle_data() even if renew_state() failed

Reviewed-by: Sage Weil <sage@redhat.com>