Fix nsxv unittest
Fix nsxv unittest

Summary:
The nsxv unittest was referencing a text address family
attribute that seems to be Cisco-specific, which is not implemented by
this platform.

Test Plan:
ran all test*.py modules in tests/ directory and saw this
passed.

ryantierney513/capirca,sneakywombat/capirca,rarcotvmw/capirca,ryantierney513/capirca,google/capirca,ryantierney513/capirca,rarcotvmw/capirca,rarcotvmw/capirca,sneakywombat/capirca,sneakywombat/capirca,google/capirca,google/capirca,google/capirca