layers: Use actual enum type name in err msg
layers: Use actual enum type name in err msg

Change-Id: I4e7933349068984d7c99577158b6ff272e1d5282

KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers