As described in document [1], the service_provider should be set to
'FIREWALL_V2:fwaas_db:neutron_fwaas.services.firewall.service_drivers.
agents.agents.FirewallAgentDriver:default' for FWaaS v2.
[1] https://docs.openstack.org/neutron/stein/admin/fwaas-v2-scenario.html#enable-fwaas-v2
Change-Id: Iad3e906af325ba3209a77a91ab2061e515b4a219
Signed-off-by: ZijianGuo <guozijn@gmail.com>