VA: Add the modifier for DMA buffer.
Copied from https://gitlab.freedesktop.org//gstreamer/gst-plugins-bad/-/merge_requests/2032
The latest and later HW needs to know the modifier of the surface when it is exported as an DMA buffer in gst. For example, the decoder may output compressed buffer, so the downstream elements such as glimagesink need to know that the buffer is compressed. Or, the render will fail or generate garbage.
We can append the modifier as a new field in caps event in negotiation.