x86 UEFI: Copy code from Linux

Copy UEFI-related definitions from Linux, so the follow-up commits can
develop UEFI function calls based on these definitions, without relying
on GNU-EFI library.

Signed-off-by: Varad Gautam <varad.gautam@suse.com>
Message-Id: <20211004204931.1537823-3-zxwang42@gmail.com>
Signed-off-by: Zixuan Wang <zxwang42@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>