blk-mq: Remove unused variable

Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

block/blk-mq.c

@@ -912,7 +912,6 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
 static void blk_mq_process_rq_list(struct blk_mq_hw_ctx *hctx)
 {
 	LIST_HEAD(rq_list);
-	LIST_HEAD(driver_list);
 
 	if (unlikely(blk_mq_hctx_stopped(hctx)))
 		return;