scsi: core: Fix a comment in function scsi_host_dev_release()

Commit 3be8828f ("scsi: core: Avoid that ATA error handling can
trigger a kernel hang or oops") moved rcu to scsi_cmnd instead of
shost. Modify "shost->rcu" to "scmd->rcu" in a comment.

Link: https://lore.kernel.org/r/1620646526-193154-1-git-send-email-chenxiang66@hisilicon.comSigned-off-by: NXiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/hosts.c

@@ -317,7 +317,7 @@ static void scsi_host_dev_release(struct device *dev)
 
 	scsi_proc_hostdir_rm(shost->hostt);
 
-	/* Wait for functions invoked through call_rcu(&shost->rcu, ...) */
+	/* Wait for functions invoked through call_rcu(&scmd->rcu, ...) */
 	rcu_barrier();
 
 	if (shost->tmf_work_q)