t10-pi: use bio_integrity_intervals() helper

Use bio_integrity_intervals() to convert blk_rq_pos(rq) to integrity
intervals to reduce code duplication.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Author: calebsander

block/t10-pi.c

@@ -542,7 +542,7 @@ static void blk_integrity_remap(struct request *rq, unsigned int nr_bytes,
 				bool prep)
 {
 	struct blk_integrity *bi = &rq->q->limits.integrity;
-	u64 ref = blk_rq_pos(rq) >> (bi->interval_exp - SECTOR_SHIFT);
+	u64 ref = bio_integrity_intervals(bi, blk_rq_pos(rq));
 	unsigned intervals = nr_bytes >> bi->interval_exp;
 	struct bio *bio;