Qt: fix opening of the last folder in open disc dialog

(cherry picked from commit 04a79492408acd2f7c911d84ca5fd6ba851b0e87)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/gui/qt4/components/open_panels.cpp

@@ -570,7 +570,7 @@ void DiscOpenPanel::updateMRL()
 void DiscOpenPanel::browseDevice()
 {
     QString dir = QFileDialog::getExistingDirectory( this,
-            qtr( I_DEVICE_TOOLTIP ) );
+            qtr( I_DEVICE_TOOLTIP ), p_intf->p_sys->filepath );
     if( !dir.isEmpty() )
     {
         ui.deviceCombo->addItem( toNativeSepNoSlash( dir ) );