Modernize non-existing IDevice::operator=()

Change-Id: Ia22ba1f307ef25348466740564072fd6fe8d6c9c
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/projectexplorer/devicesupport/idevice.h

@@ -211,7 +211,7 @@ protected:
     IDevice(const IDevice &other);
 
 private:
-    IDevice &operator=(const IDevice &); // Unimplemented.
+    IDevice &operator=(const IDevice &) = delete;
 
     int version() const;