virtio_blk: get rid of unused variable

drivers/block/virtio_blk.c: In function 'blk_done':
drivers/block/virtio_blk.c:53: warning: unused variable 'nr_bytes'

Leftover from commit 1cde26f928863d90e9e7c1217880c8450464d305

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
1 file changed