The allowed address pairs extension's API definition was rehomed into
neutron-lib with I7958a2d6f470f088ca2cb8ad638c075788f22851 and will be
consumed in neutron with I46cfeee9711973ec15881c8dc2bd0bf763bc2226
This patch switches the code over to use lib's version rather than
neutrons.
Change-Id: I3aa4c617d99fd0d3e89d20ea7bc58fad7b014629