omxvideodec: support zero-copy buffer output to the downstream plugin
omxvideodec: support zero-copy buffer output to the downstream plugin

This patch sets the Y and UV plane address of an output buffer to GstBuffer
in order to pass image data to the downstream plugin without
buffer copying.
The implementation is hard-coded as NV12 format so it's going to be
generalized later.

renesas-devel/gst-omx,renesas-devel/gst-omx