tu: Do not dereference descriptorSetLayout in push descriptors tmpl
requested to merge Danil/mesa:turnip/fix/CreateDescriptorUpdateTemplate-invalid-descriptorSetLayout into main
Fixes crash when capturing with RenderDoc.
From VK spec:
descriptorSetLayout [...] This parameter is ignored if templateType
is not VK_DESCRIPTOR_UPDATE_TEMPLATE_TYPE_DESCRIPTOR_SET.