Boot2Qt: Drop QdbDeviceDebugSupport::stop() overload

It's no-op.

Task-number: QTCREATORBUG-29168
Change-Id: I616311ee732964058d0394b5312369846ddb227d
Reviewed-by: hjk <hjk@qt.io>

src/plugins/boot2qt/qdbdevicedebugsupport.cpp

@@ -119,7 +119,6 @@ public:
 
 private:
     void start() override;
-    void stop() override;
 };
 
 QdbDeviceDebugSupport::QdbDeviceDebugSupport(RunControl *runControl)
@@ -153,13 +152,6 @@ void QdbDeviceDebugSupport::start()
     DebuggerRunTool::start();
 }
 
-void QdbDeviceDebugSupport::stop()
-{
-    // Do nothing unusual. The launcher will die as result of (gdb) kill.
-    DebuggerRunTool::stop();
-}
-
-
 // QdbDeviceQmlProfilerSupport
 
 class QdbDeviceQmlToolingSupport final : public RunWorker