libceph: adding missing message types to ceph_msg_type_name()

Some of message types are missing in ceph_msg_type_name(),
so just adding them for better understanding of output information.

Signed-off-by: Chengguang Xu <cgxu519@icloud.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>