ps3disk: use memcpy_{from,to}_bvec index

With 6e0a48552b8c (ps3disk: use memcpy_{from,to}_bvec) converting
ps3disk to new bvec helpers, incrementing the offset was accidently
lost, corrupting consecutive buffers. Restore index for non-corrupted
data transfers.

Fixes: 6e0a48552b8c (ps3disk: use memcpy_{from,to}_bvec)
Signed-off-by: René Rebe <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/block/ps3disk.c

···
 	struct bio_vec bvec;
 
 	rq_for_each_segment(bvec, req, iter) {
+		dev_dbg(&dev->sbd.core, "%s:%u: %u sectors from %llu\n",
+			__func__, __LINE__, bio_sectors(iter.bio),
+			iter.bio->bi_iter.bi_sector);
 		if (gather)
 			memcpy_from_bvec(dev->bounce_buf + offset, &bvec);
 		else
 			memcpy_to_bvec(&bvec, dev->bounce_buf + offset);
+		offset += bvec.bv_len;
 	}
 }