In this patch we fill the control structure with the bitstream paramter and
copy the bitstream data into V4L2 memory. Slice paramters are only the subset
of what Hantro needs, without any support for interlaced content.
This is a pooling allocator and the buffer pool does nothing other then
reusing the GstBuffer structure. Note that the pool is an internal pool, so
the start/stop/set_config virtual functions are not implemented.