layers: Avoid calling functions not produced by the pv codegen
layers: Avoid calling functions not produced by the pv codegen

Still need to investigate why the generator doesn't produce everything
it should, but this should be enough to get us going.

Signed-off-by: Chris Forbes <c3279c50043e18e9442c1ae071cafa0e7a4ca967@google.com>

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