libceph: nuke unused fields and functions

Either unused or useless:

    osdmap->mkfs_epoch
    osd->o_marked_for_keepalive
    monc->num_generic_requests
    osdc->map_waiters
    osdc->last_requested_map
    osdc->timeout_tid

    osd_req_op_cls_response_data()

    osdmap_apply_incremental() @msgr arg

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

net/ceph/osdmap.c

@@ -1204,8 +1204,7 @@ struct ceph_osdmap *ceph_osdmap_decode(void **p, void *end)
  * decode and apply an incremental map update.
  */
 struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
-					     struct ceph_osdmap *map,
-					     struct ceph_messenger *msgr)
+					     struct ceph_osdmap *map)
 {
 	struct crush_map *newcrush = NULL;
 	struct ceph_fsid fsid;