[Neutron] Ensure ovs agent setup runs for all CONFIG_NEUTRON_ML2_TENANT_NETWORK_TYPES

Previously we used to pick only the first type from tenant network types,
Now packstack parses whole array and sets ovs agent on nodes accordingly.

Closes-Bug: rhbz#1163697 rhbz#1168242
Change-Id: I15be465c7d910cee7224c0bf78e2a6a9d93f9bb4
(cherry picked from commit 730f1497a943af7e4c53b25a03255ed400ecdc79)