Unhook the SCSI CD driver from the disk "mini-layer" and/or GEOM.

Unhook the SCSI CD driver from the disk "mini-layer" and/or GEOM.

SCSI disks are too square pegs for the round holes in both of these.

And since atapi-cd has clearly shown that there are better acccess
models for CD media than trying to pretend to be a classical disk,
we stop the masquerade rather than patch up the costume.

But do implement the DIOCGMEDIASIZE and DIOCGSECTORSIZE so it will
be possible to manually attach to GEOM, should some the need arise.

Ideally, this driver should do media-detection and call make_dev()
when a CD is inserted and destroy_dev() when it is removed, this
would allow our future devd(8) to automount etc etc but coding that
takes SCSI-clue beyond anything I posses.

Tested on:      sparc64