Boot2Qt: Simplify QdbDeviceDebugSupport

Remove setting the remote channel and qml server.
This is already done by its superclass, inside:
DebuggerRunTool::continueAfterTerminalStart().

Task-number: QTCREATORBUG-29168
Change-Id: I9ed25599d0da920af2eee7908e127cc0e3f46805
Reviewed-by: hjk <hjk@qt.io>

src/plugins/boot2qt/qdbdevicedebugsupport.cpp

@@ -136,14 +136,9 @@ void QdbDeviceDebugSupport::start()
 {
     setStartMode(Debugger::AttachToRemoteServer);
     setCloseMode(KillAndExitMonitorAtClose);
-    if (usesDebugChannel())
-        setRemoteChannel(debugChannel());
-    if (usesQmlChannel())
-        setQmlServer(qmlChannel());
     setUseContinueInsteadOfRun(true);
     setContinueAfterAttach(true);
     addSolibSearchDir("%{sysroot}/system/lib");
-
     DebuggerRunTool::start();
 }