headers: Fix a typo in vk_icd.h
headers: Fix a typo in vk_icd.h

Change-Id: I9ede42e379605329ffd25a9466e0971b3ab7dd77

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