omxvideoenc: pass padding requirements to ALLOCATION query

By passing the expected video buffer layout, the upstream producer
may be able to produce buffers fitting those requierements allowing
gst-omx to use dynamic buffer mode rather than having to copy each input

This is particularly useful with v4l2src as it can request the capture
driver to produce buffers with the required paddings.
8 jobs for vmeta-plane-height-master in 11 minutes and 12 seconds (queued for 6 seconds)