Description of problem:
When deploying an overcloud using mistral derive parameter plan in order to derive DPDK parameters, mistral plan derives an incorrect value which causes puppet-neutron to fail the deployment.

Example of working NeutronPhysnetNUMANodesMapping supplied manually:
NeutronPhysnetNUMANodesMapping: {dpdk-mgmt: [0]}

Which will be translated to the following hieradata:
    "nova::compute::neutron_physnets_numa_nodes_mapping": {
            "dpdk-mgmt": [
                0
            ]
        }

Example of derived NeutronPhysnetNUMANodesMapping that is failing:
NeutronPhysnetNUMANodesMapping:
- dpdk-mgmt:
  - 0
(In JSON equals to: [{dpdk-mgmt: [0]}]

Which will be translated to the following hieradata:
    "nova::compute::neutron_physnets_numa_nodes_mapping": [
        {
            "dpdk-mgmt": [
                0
            ]
        }
    ]



Version-Release number of selected component (if applicable):
RHOS_TRUNK-16.0-RHEL-8-20191112.n.1

How reproducible:
Compose: RHOS_TRUNK-16.0-RHEL-8-20191112.n.1

Steps to Reproduce:
1. Deploy Undercloud.
2. Deploy Overcloud with mistral derived parameters for DPDK.

Actual results:
Deployment is failing.

Expected results:
Deployment is successful and parameters are derived correctly.

Additional info: