ceph: fix debugfs warnings

Include "super.h" outside of CONFIG_DEBUG_FS to eliminate a compiler warning:

fs/ceph/debugfs.c:266: warning: 'struct ceph_fs_client' declared inside parameter list
fs/ceph/debugfs.c:266: warning: its scope is only this definition or declaration, which is probably not what you want
fs/ceph/debugfs.c:271: warning: 'struct ceph_fs_client' declared inside parameter list

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>