target: Fix iblock se_dev_attrib.unmap_granularity

The block layer keeps q->limits.discard_granularity in bytes, but iblock
(and the SCSI Block Limits VPD page) keep unmap_granularity in blocks.
Report the correct value when exporting block devices by dividing to
convert bytes to blocks.

Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_iblock.c

@@ -181,7 +181,7 @@ static struct se_device *iblock_create_virtdevice(
 		 */
 		dev->se_sub_dev->se_dev_attrib.max_unmap_block_desc_count = 1;
 		dev->se_sub_dev->se_dev_attrib.unmap_granularity =
-				q->limits.discard_granularity;
+				q->limits.discard_granularity >> 9;
 		dev->se_sub_dev->se_dev_attrib.unmap_granularity_alignment =
 				q->limits.discard_alignment;