UEFI 2.8 only supports Intel, ARM and RISC-V
https://review.opendev.org/c/openstack/tripleo-common/+/773010/
... to break ppc64le IPA image builds.
Signed-off-by: Lon Hohberger <lhh@redhat.com>
Change-Id: Ia74d6aa659f5d705eeea931a4332f08b8bdcb2a3