Qt: Fix Fullscreen not on the correct display

Replace setPosition with setGeometry. This makes sure when rendering to main window, it stays on the current display the main window is currently positioned at.

Author: jasaaved

pcsx2-qt/MainWindow.cpp

@@ -2583,7 +2583,7 @@ void MainWindow::createDisplayWidget(bool fullscreen, bool render_to_main)
 
 #ifdef DISPLAY_SURFACE_WINDOW
 		if (isVisible() && g_emu_thread->shouldRenderToMain())
-			m_display_surface->setPosition(screen()->availableGeometry().topLeft());
+			m_display_surface->setGeometry(screen()->geometry());
 		else
 			restoreDisplayWindowGeometryFromConfig();