iscsi-target: Use list_first_entry() where appropriate

Instead of using the obfuscated pattern of

	list_for_each_entry(var, list, ...)
		break;

to set var to the first entry of a list, use the straightforward

	var = list_first_entry(list, ...);
Reported-by: Joern Engel <joern@logfs.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target_tq.c

@@ -66,8 +66,7 @@ static struct iscsi_thread_set *iscsi_get_ts_from_inactive_list(void)
 		return NULL;
 	}
 
-	list_for_each_entry(ts, &inactive_ts_list, ts_list)
-		break;
+	ts = list_first_entry(&inactive_ts_list, struct iscsi_thread_set, ts_list);
 
 	list_del(&ts->ts_list);
 	iscsit_global->inactive_ts--;

drivers/target/iscsi/iscsi_target_util.c

@@ -500,8 +500,8 @@ struct iscsi_queue_req *iscsit_get_cmd_from_immediate_queue(struct iscsi_conn *c
 		spin_unlock_bh(&conn->immed_queue_lock);
 		return NULL;
 	}
-	list_for_each_entry(qr, &conn->immed_queue_list, qr_list)
-		break;
+	qr = list_first_entry(&conn->immed_queue_list,
+			      struct iscsi_queue_req, qr_list);
 
 	list_del(&qr->qr_list);
 	if (qr->cmd)
@@ -575,8 +575,8 @@ struct iscsi_queue_req *iscsit_get_cmd_from_response_queue(struct iscsi_conn *co
 		return NULL;
 	}
 
-	list_for_each_entry(qr, &conn->response_queue_list, qr_list)
-		break;
+	qr = list_first_entry(&conn->response_queue_list,
+			      struct iscsi_queue_req, qr_list);
 
 	list_del(&qr->qr_list);
 	if (qr->cmd)