Bluetooth: Host: Guard set state in conn_destroy

If bt_conn_set_state(conn, BT_CONN_DISCONNECTED) is called
while the connection is already disconnected, this triggers
a warning. This is likely to happen when bt_conn_cleanup_all
is called as part of bt_disable.

Added the state check to avoid unnecessary warnings in the log.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>

Author: Thalley

subsys/bluetooth/host/conn.c

@@ -852,7 +852,9 @@ static void conn_destroy(struct bt_conn *conn, void *data)
 		bt_conn_set_state(conn, BT_CONN_DISCONNECT_COMPLETE);
 	}
 
-	bt_conn_set_state(conn, BT_CONN_DISCONNECTED);
+	if (conn->state != BT_CONN_DISCONNECTED) {
+		bt_conn_set_state(conn, BT_CONN_DISCONNECTED);
+	}
 }
 
 void bt_conn_cleanup_all(void)