sd: Optimal I/O size is in bytes, not sectors

Commit ca369d5 ("block/sd: Fix device-imposed transfer length
limits") accidentally switched optimal I/O size reporting from bytes to
block layer sectors.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Fixes: ca369d5
Cc: stable@vger.kernel.org # 4.4+
Reviewed-by: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Reviewed-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>

drivers/scsi/sd.c

@@ -2893,7 +2893,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	    sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS &&
 	    sdkp->opt_xfer_blocks * sdp->sector_size >= PAGE_CACHE_SIZE)
 		rw_max = q->limits.io_opt =
-			logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
+			sdkp->opt_xfer_blocks * sdp->sector_size;
 	else
 		rw_max = BLK_DEF_MAX_SECTORS;