InputConfigDialog pass the device_cbox to the wiimote extension dialogs

This fixes a crash when trying to open the advanced input config dialog on the wiimote extensions.  The device_cbox wasn't initialised and it should have been with the wiimote one.

Source/Core/DolphinWX/Input/GuitarInputConfigDiag.h

@@ -6,9 +6,11 @@
 
 #include "DolphinWX/Input/InputConfigDiag.h"
 
+class wxComboBox;
+
 class GuitarInputConfigDialog final : public InputConfigDialog
 {
 public:
   GuitarInputConfigDialog(wxWindow* parent, InputConfig& config, const wxString& name,
-                          int port_num = 0);
+                          wxComboBox* device_cbox_parent, int port_num = 0);
 };