Since we no longer drop the request mutex between registering and
mapping an osd request in ceph_osdc_start_request(), there is no
chance of a race with kick_requests().

We can now therefore map and send the new request unconditionally
(but we'll issue a warning should it ever occur).
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-off-by: NSage Weil <sage@inktank.com>