ceph/super.c: quiet sparse noise

Quiet the sparse noise:

warning: symbol 'create_fs_client' was not declared. Should it be static?
warning: symbol 'destroy_fs_client' was not declared. Should it be static?

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Sage Weil <sage@newdream.net>
ceph-devel@vger.kernel.org
Signed-off-by: Sage Weil <sage@newdream.net>