glcontext: egl: Unrestrict the support base DRM formats
There is no requirement for a base DRM format to be supported by libgstvideo in order to be uploaded to. Don't limite to DRM fourcc that have a libgstvideo format mapping. This notably enabled AFBC support, which uses an opaque based format that does not have a linear definition. This also adds R8/RG88 and simimlar other formats that are not yet mapped in libgstvideo.
cc @vjaquez