the port for floating IP should not include IPv6 address

[shihanzhang]

Now if we create a floating IP, neutron will create a internal port for this floating IP which is used purely for internal system and admin use when managing floating IPs, but if a external network with a IPv4 subnet and a IPv6 subnet, then the port for floating IP will
has two IPs, one is IPv4, one is IPv6.
reproduce steps:
1. create a external network
2. create a IPv4 subnet and a IPv6 subnet for this network
3. create a floatingIP without paramter '--floating-ip-address'

you will find the port for this floatingIP will has two IPs

[Sridhar Gaddam (sridhargaddam)]

Issue is addressed with the following patch - https://review.openstack.org/#/c/198908/