block: remove unused members for io_context

After removing blk-sq code, there is no user of nr_batch_requests
and last_waited in kernel.

Signed-off-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Yufen Yu

include/linux/iocontext.h

@@ -106,12 +106,6 @@ struct io_context {
 
 	unsigned short ioprio;
 
-	/*
-	 * For request batching
-	 */
-	int nr_batch_requests;     /* Number of requests left in the batch */
-	unsigned long last_waited; /* Time last woken after wait for request */
-
 	struct radix_tree_root	icq_tree;
 	struct io_cq __rcu	*icq_hint;
 	struct hlist_head	icq_list;