vk-layer-generate.py: drop vk prefix for layer functions
vk-layer-generate.py: drop vk prefix for layer functions

Drop VK_LAYER_EXPORT as well.

Radamanthe/VulkanSamples,Radamanthe/VulkanSamples,Radamanthe/VulkanSamples,Radamanthe/VulkanSamples,Radamanthe/VulkanSamples,Radamanthe/VulkanSamples