block: remove the BLKPREP_* values.

Unused now.
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NBart Van Assche <bvanassche@acm.org>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

include/linux/blkdev.h

@@ -776,16 +776,6 @@ static inline unsigned int blk_queue_depth(struct request_queue *q)
 	return q->nr_requests;
 }
 
-/*
- * q->prep_rq_fn return values
- */
-enum {
-	BLKPREP_OK,		/* serve it */
-	BLKPREP_KILL,		/* fatal error, kill, return -EIO */
-	BLKPREP_DEFER,		/* leave on queue */
-	BLKPREP_INVALID,	/* invalid command, kill, return -EREMOTEIO */
-};
-
 extern unsigned long blk_max_low_pfn, blk_max_pfn;
 
 /*