vulkaninfo: Fix variable, struct and function names
vulkaninfo: Fix variable, struct and function names

Cleanup to match Google c++ style guide.

Change-Id: Ifecbf5c8680159684e24a184421e907d1d815627

KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools