Puts back previously deferred DATA frame in the stream *stream_id*
to the outbound queue.

This function returns 0 if it succeeds, or one of the following
negative error codes:

:enum:`nghttp2_error.NGHTTP2_ERR_INVALID_ARGUMENT`
    The stream does not exist; or no deferred data exist.
:enum:`nghttp2_error.NGHTTP2_ERR_NOMEM`
    Out of memory.