libceph: rename ceph_client_id() -> ceph_client_gid()

It's gid / global_id in other places.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>
3 files changed