dm: remove useless code from dm_dispatch_clone_request

Both ->start_time_ns and the RQF_IO_STAT are set when the request is
allocated using blk_mq_alloc_request by dm-mpath in blk_mq_rq_ctx_init.
The block layer also ensures ->start_time_ns is only set when actually
needed.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20220215100540.3892965-5-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/md/dm-rq.c

@@ -307,10 +307,6 @@ static blk_status_t dm_dispatch_clone_request(struct request *clone, struct requ
 {
 	blk_status_t r;
 
-	if (blk_queue_io_stat(clone->q))
-		clone->rq_flags |= RQF_IO_STAT;
-
-	clone->start_time_ns = ktime_get_ns();
 	r = blk_insert_cloned_request(clone);
 	if (r != BLK_STS_OK && r != BLK_STS_RESOURCE && r != BLK_STS_DEV_RESOURCE)
 		/* must complete clone in terms of original request */