TWin: Fix loading of window decoration configuration libraries

Accidentally broken by commit 84ab47055d.

Signed-off-by: Mavridis Philippe <mavridisf@gmail.com>

twin/kcmtwin/twindecoration/twindecoration.cpp

@@ -938,10 +938,7 @@ void KWinDecorationModule::checkSupportedBorderSizes()
 
 TQString KWinDecorationModule::styleToConfigLib( TQString& styleLib )
 {
-        if( styleLib.startsWith( "twin_" ))
-            return "twin_" + styleLib.mid( 6 ) + "_config";
-        else
-            return styleLib + "_config";
+        return styleLib + "_config";
 }
 
 TQString KWinDecorationModule::quickHelp() const