tests: NullRenderPass expected error message
tests: NullRenderPass expected error message

Update VkLayerTest.NullRenderPass to expect the error message from
parameter validation in anticipation that the duplicate check in core
validation will be removed.

Change-Id: I3267d28cf8b129882e2044901ba0fc26c9ffdc21

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