only do atomic pageflip for now

Until we re-introduce blob property support, setcrtc the old way to
setup initial mode, and then control planes via atomic
some fixes
hit it more with a hammer

Seemed to be some crtc-id (idr id) vs index confusion in plane picking.
So fix that mostly.  Since I wasn't entirely sure what the purpose of
reuse_old_plane(), just drop it.