layers: Remove duplicate check and dead code
layers: Remove duplicate check and dead code

Change-Id: Ib25a9fc9052897eccb244d85122b451bda02f892

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