Fix assert in tst_QQuickRenderControl

We should not call device functions after resetting them.

Change-Id: I0470792457eff070ba3aeb767f5f5be622ebda42
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

tests/auto/quick/qquickrendercontrol/tst_qquickrendercontrol.cpp

@@ -650,9 +650,8 @@ void tst_RenderControl::renderAndReadBackWithVulkanNative()
     }
 
     // now that everything is destroyed, get rid of the VkDevice too
-    vulkanInstance.resetDeviceFunctions(dev);
     df->vkDestroyDevice(dev, nullptr);
-
+    vulkanInstance.resetDeviceFunctions(dev);
 #else
     QSKIP("No Vulkan support in Qt build, skipping native Vulkan test");
 #endif