[dxvk] Actually fix multidraw workaround

Otherwise we'll end up using the feature anyway.

src/dxvk/dxvk_adapter.cpp

@@ -406,8 +406,10 @@ namespace dxvk {
     }
 
     // Enable multi-draw for draw batching
+    if (devExtensions.extMultiDraw) {
       enabledFeatures.extMultiDraw.multiDraw =
         m_deviceFeatures.extMultiDraw.multiDraw;
+    }
 
     // Enable memory priority and pageable memory if supported
     // to improve driver-side memory management