Add LINUX_EFI_INITRD_MEDIA_GUID to our collection of GUID definitions, it can be used in a media device path to specify a Linux style initrd that can be loaded by the OS using the LoadFile2 protocol. Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2564 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Laszlo Ersek <lersek@redhat.com>