Description of problem:

openshift-install create manifests step is failing with 4.19.0-rc.5 OR 4.19.0

Version-Release number of selected component (if applicable):

4.19.0-rc.5 OR 4.19.0

How reproducible:

Always reproducible   

Steps to Reproduce:

1. Followed the KC documentation for LPAR SNO installation. Prepare the install-config.yaml file by referencing the KC document.    

2. Create manifests using the openshift installer - openshift-install create manifests --dir=/root/ocpinst/.
    Note - install-config.yaml is present inside the /root/ocpinst/ directory.

Actual results:

failed to fetch Master Machines: failed to generate asset "Master Machines": this install method does not support Single Node installation on platform none   

Expected results:

Manifests created in: /root/ocpinst, /root/ocpinst/manifests and /root/ocpinst/openshift

Additional info:
4.19.0-rc.5 build has changes for SNO, find the details below,
OCP ticket - https://issues.redhat.com/browse/OCPBUGS-56811
Pull Request - https://github.com/openshift/installer/pull/9756