block: optimize blk_queue_zoned_model for !CONFIG_BLK_DEV_ZONED

Always return BLK_ZONED_NONE if zoned device support is not enabled.
This allows various compiler optimizations including the dead code
elimination that we so like for avoiding ifdefs.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NKeith Busch <kbusch@kernel.org>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Reviewed-by: NChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: NDamien Le Moal <damien.lemoal@wdc.com>

include/linux/blkdev.h

@@ -692,7 +692,9 @@ static inline bool queue_is_mq(struct request_queue *q)
 static inline enum blk_zoned_model
 blk_queue_zoned_model(struct request_queue *q)
 {
-	return q->limits.zoned;
+	if (IS_ENABLED(CONFIG_BLK_DEV_ZONED))
+		return q->limits.zoned;
+	return BLK_ZONED_NONE;
 }
 
 static inline bool blk_queue_is_zoned(struct request_queue *q)