Complete the x86/KVM section with SEV-related files.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20211007161716.453984-24-philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>