When doing direct dmabuf upload, we rely on the GL stack for doing the color
transformation. The caps we transform from GL to DMABuf are always with a format
of RGBA. Instead of listing all GstVideoFormat and translating them back into
DRM formats, simply list all supported DRM format for the context.
This enable rendering DRM formats that don't have an shader based emulation
implemented such as NV15.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/9306>
7f18dc5411