zircon-uefi: mirror of the zircon UEFI headers

There’s a new mirror of the Google Fuschsia UEFI headers:

https://github.com/no92/zircon-uefi

See-also:

https://fuchsia.googlesource.com/zircon/+/master/docs/ddk/driver-development.md

https://en.wikipedia.org/wiki/Google_Fuchsia

UEFI bootloader for Google Fuchsia