Neutron API is accepting 'security_groups' field in
order to return the list of security_groups attached
to a port, but openstackclient is parsing the output
over a Openstack Port object that has security_group_ids
to map. This patch sends to the Neutron API the expected
field value and replace the output key to allow the
mapping just in case '--long' argument is passed.
Closes-Bug: #2095414
Change-Id: I188edc3c620ce29d7b16497ca24fd7d972a06618