venus: ensure to clear VkPipelineCreationFeedback::flags if needed
clean up the garbage in the flags which could be uninitialized.
Fixes: d0cb99e9 ("venus: Enable VK_EXT_pipeline_creation_feedback")
Test: dEQP-VK.pipeline.creation_feedback.*
=============== Summary ===============
Total Run time: 51s
1/1 modules completed
Total Tests : 12
PASSED : 12
FAILED : 0
============== End of Results ==============