This also needed a change to calculating the strides, as IYU1 is 12bpp,
and GstVideoInfo defines pixel stride in bytes, so for IYU2 the stride
was calculated as zero. Instead use Pleora's own definition of pixel
stride to calculate Pleora's row stride.
For example, a Mono8 642x482 would have failed to work, as GStreamer
expects the stride to be a multiple of 4-bytes, that is 644 bytes in
this example, while Pleora doesn't do this alignment. This incurs a copy
unfortunately, and there might be a way with memory meta to avoid this,
however eventually most elements will need to have the data 4-byte
aligned.
