Finishes deferred initialization.

def _finish_deferred_init(self):
        """Finishes deferred initialization."""
        if not self._deferred_init:
            return
        init, ctx, default_init, data = self._deferred_init
        self._deferred_init = ()
        assert self.shape is not None and np.prod(self.shape) > 0, \
            "Cannot initialize Parameter '%s' because it has " \
            "invalid shape: %s. Please specify in_units, " \
            "in_channels, etc for `Block`s."%(
                self.name, str(self.shape))

        with autograd.pause():
            if data is None:
                data = ndarray.zeros(shape=self.shape, dtype=self.dtype,
                                     ctx=context.cpu(), stype=self._stype)
                initializer.create(default_init)(
                    initializer.InitDesc(self.name, {'__init__': init}), data)

            self._init_impl(data, ctx)