use only one thread

DownloadDCFirmware/worker_thread.h

@@ -0,0 +1,20 @@
+#ifndef WORKER_THREAD_H_INCLUDED
+#define WORKER_THREAD_H_INCLUDED
+
+#include <QThread>
+
+class WorkerThread : public QThread {
+    Q_OBJECT
+
+public:
+    explicit WorkerThread(QObject *parent = nullptr);
+    ~WorkerThread();
+
+
+private:
+    void run() override;
+
+    bool m_quit = false;
+};
+
+#endif // WORKER_THREAD_H_INCLUDED