fix ValueError

this patch fixes the following error:

[req-076d932f-97e5-4d99-a18d-45fef123f8aa None] Error in agent event loop
Traceback (most recent call last):
  File "/opt/stack/neutron/neutron/plugins/ryu/agent/ryu_ml2_agent.py", line 1292, in rpc_loop
    sync = self.process_network_ports(port_info)
  File "/opt/stack/neutron/neutron/plugins/ryu/agent/ryu_ml2_agent.py", line 1191, in process_network_ports
    resync_a = self.treat_devices_added(port_info['added'])
  File "/opt/stack/neutron/neutron/plugins/ryu/agent/ryu_ml2_agent.py", line 1113, in treat_devices_added
    details['admin_state_up'])
  File "/opt/stack/neutron/neutron/plugins/ryu/agent/ryu_ml2_agent.py", line 1015, in treat_vif_port
    physical_network, segmentation_id)
  File "/opt/stack/neutron/neutron/plugins/ryu/agent/ryu_ml2_agent.py", line 700, in port_bound
    physical_network, segmentation_id)
  File "/opt/stack/neutron/neutron/plugins/ryu/agent/ryu_ml2_agent.py", line 461, in provision_local_vlan
self.tun_br.ofparser.OFPActionOutput(int(ofports), 0)]
ValueError: invalid literal for int() with base 10: '3,2'