sd: Fix discard granularity when LBPRZ=1

Commit 397737223c59 ("sd: Make discard granularity match logical block
size when LBPRZ=1") accidentally set the granularity to one byte instead
of one logical block on devices that provide deterministic zeroes after
UNMAP.

Signed-off-by: Martin K. Petersen <[e-mail]>
Reported-by: Mike Snitzer <[e-mail]>
Reviewed-by: Ewan Milne <[e-mail]>
Reviewed-by: Bart Van Assche <[e-mail]>
Fixes: 397737223c59e89dca7305feb6528caef8fbef84
Cc: <[e-mail]> #v4.4+

drivers/scsi/sd.c

···
 	 */
 	if (sdkp->lbprz) {
 		q->limits.discard_alignment = 0;
-		q->limits.discard_granularity = 1;
+		q->limits.discard_granularity = logical_block_size;
 	} else {
 		q->limits.discard_alignment = sdkp->unmap_alignment *
 			logical_block_size;