asahi: Flip kmsro around to allocate on the GPU
Our display controller can handle arbitrary GPU imports, so there is no reason to use dumb KMS buffers. Allocate everything on the GPU instead.
This also allows us to be lazy about mapping things to the KMS side, so only clients that really want a KMS handle actually do that, which stops us from ending up with a bunch of junk mapped to DCP (e.g. X11 clients always request SCANOUT even under XWayland).
(Unfortunately, XWayland still ends up requesting KMS handles, but that's a different problem now...)
Depends on !26 (merged) which depends on !21 (merged) because silly reasons again ^^;;
Signed-off-by: Asahi Lina lina@asahilina.net