PPC64LE Overcloud images validation fails. Specifically in Queens

[Brendan Shephard]

Description
===========
During the Overcloud deployment. Image validation fails for PPC64LE images as the check for bm-deploy-kernal and bm-deploy-ramdisk are both hard-coded. There needs the be an additional check for multi-arch support.

This is only an issue in Queens where we are still using tripleo-common for validations. It seems to be resolved in tripleo-validation (https://opendev.org/openstack/tripleo-validations/commit/9750f945db25d1405312a6df738d7c6aaeb1a7f0) after Queens.

Steps to reproduce
==================
- Upload PPC images to Glance
- Import PPC nodes into Ironic
- Run the deployment

Expected result
===============
Validations should confirm that the architecture of the nodes is PowerPC, and then check for the relevant images based on that result

Actual result
=============
It just checks the images against the x86 ones and then fails with the following error:
[{u'errors': [u'Node <PPC_UUID_0> has an incorrectly configured driver_info/deploy_ramdisk. Expected "bm-deploy-ramdisk" but got "ppc64le-bm-deploy-ramdisk".', u'Node <PPC_UUID_0> has an incorrectly configured driver_info/deploy_kernel. Expected "bm-deploy-kernel" but got "ppc64le-bm-deploy-kernel".']

Environment
===========
- RHOSP 13 (Queens)
- openstack-tripleo-common-8.7.1-20.el7ost.noarch

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/queens
Review: https://review.opendev.org/754885

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Brendan Shephard <email address hidden>" on branch: stable/queens
Review: https://review.opendev.org/c/openstack/tripleo-common/+/754885
Reason: Better solution found