block: blk-mq: Remove blk_mq_sched_started_request and started_request

blk_mq_sched_completed_request is a function that checks if the elevator
related to the request has started_request implemented, but currently, none of
the available IO schedulers implement started_request, so remove both.

Signed-off-by: Marcos Paulo de Souza <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

block/blk-mq-sched.h

···
 		e->type->ops.completed_request(rq, now);
 }
 
-static inline void blk_mq_sched_started_request(struct request *rq)
-{
-	struct request_queue *q = rq->q;
-	struct elevator_queue *e = q->elevator;
-
-	if (e && e->type->ops.started_request)
-		e->type->ops.started_request(rq);
-}
-
 static inline void blk_mq_sched_requeue_request(struct request *rq)
 {
 	struct request_queue *q = rq->q;

block/blk-mq.c

···
 {
 	struct request_queue *q = rq->q;
 
-	blk_mq_sched_started_request(rq);
-
 	trace_block_rq_issue(q, rq);
 
 	if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {

include/linux/elevator.h

···
 	struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
 	bool (*has_work)(struct blk_mq_hw_ctx *);
 	void (*completed_request)(struct request *, u64);
-	void (*started_request)(struct request *);
 	void (*requeue_request)(struct request *);
 	struct request *(*former_request)(struct request_queue *, struct request *);
 	struct request *(*next_request)(struct request_queue *, struct request *);