layers: GH7, Fix bad var names in swapchain layer
layers: GH7, Fix bad var names in swapchain layer

Change-Id: I46331c530654334abacbfb3ffd3656809f6b7d5d

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