remove a few uses of ->queuedata

[Christoph Hellwig]

Hi all,

various bio based drivers use queue->queuedata despite already having
set up disk->private_data, which can be used just as easily.  This
series cleans them up to only use a single private data pointer.

blk-mq based drivers that have code pathes that can't easily get at
the gendisk are unaffected by this series.