block: remove REQ_NOWAIT_INLINE

We had a few issues with this code, and there's still a problem around
how we deal with error handling for chained/split bios. For now, just
revert the code and we'll try again with a thoroug solution. This
reverts commits:

e15c2ffa1091 ("block: fix O_DIRECT error handling for bio fragments")
0eb6ddfb865c ("block: Fix __blkdev_direct_IO() for bio fragments")
6a43074e2f46 ("block: properly handle IOCB_NOWAIT for async O_DIRECT IO")
893a1c97205a ("blk-mq: allow REQ_NOWAIT to return an error inline")

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-mq.c b/block/blk-mq.c
index a8e6a58..0835f4d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1958,13 +1958,9 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 	rq = blk_mq_get_request(q, bio, &data);
 	if (unlikely(!rq)) {
 		rq_qos_cleanup(q, bio);
-
-		cookie = BLK_QC_T_NONE;
-		if (bio->bi_opf & REQ_NOWAIT_INLINE)
-			cookie = BLK_QC_T_EAGAIN;
-		else if (bio->bi_opf & REQ_NOWAIT)
+		if (bio->bi_opf & REQ_NOWAIT)
 			bio_wouldblock_error(bio);
-		return cookie;
+		return BLK_QC_T_NONE;
 	}
 
 	trace_block_getrq(q, bio, bio->bi_opf);