vulkaninfo: Fix HTML output warnings and errors
vulkaninfo: Fix HTML output warnings and errors

Updated vulkaninfo HTML output to fix errors and
warnings output by https://validator.w3.org.

Change-Id: Ic84cc71467e69a33d2c816e8e79b918006c3194e

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