drm/nouveau/kms/nv04-nv40: prevent undisplayable framebuffers from creation

Pre-nv50 YUV overlays have stringent requirements for working with the
internal machinery. Instead of rejecting these at update_plane time, we
should instead prevent the framebuffers from being created in the first
place.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>