Add support to simple-dmabuf-v4l for NV12 devices that combine planes in a dmabuf.
There are V4L2 devices that will output NV12 but will do so using one dma buffer. To support this, we need to add the same dma buffer twice but with a different offset for the chrominance plane.
Fixes wayland/weson#712 Signed-off-by: Bram Stolk (b.stolk@gmail.com)
Edited by Bram Stolk