rnbd-srv: remove the name field from struct rnbd_dev

rnbd-srv: remove the name field from struct rnbd_dev

Just print the block device name directly using the %pg format specifier.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20220713055317.1888500-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>