Various collection of renderonly fixes
I've audited all renderonly capable drivers except vc4/v3d (someone else working on this right now).
It seems like they all return a handle valid for the internal render-only FD when the user asks one for the KMS FD. Fix this to fail if we don't have a scanout handle, instead of returning a bad handle. (vc4/v3d gets this right.)
Two other related etnaviv fixes are included as well.
I haven't tested these patches, as I don't have the necessary hardware for all of these. I'll try lima shortly.