libceph: update ceph_mds_state_name() and ceph_mds_op_name()

Update ceph_mds_state_name() and ceph_mds_op_name() to include the
newly-added definitions in "ceph_fs.h", and to match its counterpart
in the user space code.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>