pktcdvd: stop setting q->queuedata

The two users can get the private data from the gendisk with one less
pointer dereference, and we can drop the useless q parameter from
pkt_make_request_write.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240222073647.3776769-2-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>