Updated platformid to force openstack for s390x on 4.2#1004

jlebon merged 2 commits intocoreos:rhcos-4.2-multiarchcoreos/coreos-assembler:rhcos-4.2-multiarchfrom

RedHat-MultiArch-QE:jpz-force-qemu-platformid-to-openstack-s390xRedHat-MultiArch-QE/coreos-assembler:jpz-force-qemu-platformid-to-openstack-s390xCopy head branch name to clipboard