pcmcia: ds: fix refcount leak in pcmcia_device_add()
As the comment of device_register() says, it should use put_device()
to give up the reference in the error path. Then, insofar resources
will be freed in pcmcia_release_dev(), the error path is no longer
needed. In particular, this means that the (previously missing) dropping
of the reference to &p_dev->function_config->ref is now handled by
pcmcia_release_dev().