block: move bio_mergeable out of bio.h

bio_mergeable is only needed by I/O schedulers, so move it to
blk-mq-sched.h.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211012161804.991559-4-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq-sched.h

@@ -37,6 +37,11 @@ static inline void blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx)
 		__blk_mq_sched_restart(hctx);
 }
 
+static inline bool bio_mergeable(struct bio *bio)
+{
+	return !(bio->bi_opf & REQ_NOMERGE_FLAGS);
+}
+
 static inline bool
 blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio,
 		unsigned int nr_segs)

include/linux/bio.h

@@ -69,14 +69,6 @@ static inline bool bio_no_advance_iter(const struct bio *bio)
 	       bio_op(bio) == REQ_OP_WRITE_ZEROES;
 }
 
-static inline bool bio_mergeable(struct bio *bio)
-{
-	if (bio->bi_opf & REQ_NOMERGE_FLAGS)
-		return false;
-
-	return true;
-}
-
 static inline unsigned int bio_cur_bytes(struct bio *bio)
 {
 	if (bio_has_data(bio))