Remove DVDInterface::ChangeDiscAsHost

There isn't much point in keeping this utility function around
now that RunAsCPUThread provides a simple way of running things
on the CPU thread.

Source/Core/DolphinWX/Frame.cpp

@@ -143,7 +143,7 @@ void CRenderFrame::OnDropFiles(wxDropFilesEvent& event)
   }
   else
   {
-    DVDInterface::ChangeDiscAsHost(filepath);
+    Core::RunAsCPUThread([&filepath] { DVDInterface::ChangeDisc(filepath); });
   }
 }
 

Source/Core/DolphinWX/FrameTools.cpp

@@ -369,7 +369,7 @@ void CFrame::DoOpen(bool Boot)
   }
   else
   {
-    DVDInterface::ChangeDiscAsHost(WxStrToStr(path));
+    Core::RunAsCPUThread([&path] { DVDInterface::ChangeDisc(WxStrToStr(path)); });
   }
 }
 

Source/Core/DolphinWX/GameListCtrl.cpp

@@ -1557,7 +1557,7 @@ void GameListCtrl::OnChangeDisc(wxCommandEvent& WXUNUSED(event))
   const GameListItem* iso = GetSelectedISO();
   if (!iso || !Core::IsRunning())
     return;
-  DVDInterface::ChangeDiscAsHost(WxStrToStr(iso->GetFileName()));
+  Core::RunAsCPUThread([&iso] { DVDInterface::ChangeDisc(WxStrToStr(iso->GetFileName())); });
 }
 
 void GameListCtrl::OnSize(wxSizeEvent& event)