Fix awk string to correctly extract PORT_ID

This one-character change addresses the issue where this script always fails to get the PORT_ID.  The output table looks like this:
 fixed_ips                                                                        | id                                   | tenant_id                        |
| {"subnet_id": "f2fe6ee6-ee3a-4f8d-bc6f-f537cb230319", "ip_address": "10.2.7.1"}  | 0e6c6a53-d8d4-4a0d-be70-330f6961432f | ca07deedf3864058a8e62797d1711733 |

As you can see we need the 7th field, not the 2nd.