null_blk: remove an unused variable assignment in null_add_dev

Fix up the recent blk_alloc_disk conversion.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210614060231.3965278-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1 file changed