Revert "pktcdvd: remove driver."

This reverts commit f40eb998.

There are apparently still users out there of this driver. While we'd
love to remove it to ease the maintenance burden, let's reinstate it
for now until better (userspace) solutions can be developed.

Link: https://lore.kernel.org/lkml/20230104190115.ceglfefco475ev6c@pali/


Reported-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>