radv/gfx10: fix VK_KHR_pipeline_executable_properties with NGG GS

No GS copy shader if a pipeline enables NGG GS.

This fixes
dEQP-VK.pipeline.executable_properties.graphics.*geometry_stage*.

Fixes: 86864eed ("radv: Implement radv_GetPipelineExecutablePropertiesKHR.")
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
(cherry picked from commit 99c186fb)