[vs]: add teamd test on vs platform

[lguohan]

Signed-off-by: Guohan Lu [email protected]

- What I did
add teamd test on vs platform

- How I did it

- How to verify it

lgh@gulv-vm1:/data/sonic/sonic-buildimage/platform/vs/tests$ sudo py.test -v
================================================= test session starts =================================================
platform linux2 -- Python 2.7.12, pytest-3.3.1, py-1.5.2, pluggy-0.6.0 -- /usr/bin/python
cachedir: .cache
rootdir: /data/sonic/sonic-buildimage/platform/vs/tests, inifile:
collected 2 items                                                                                                     

bgp/test_invalid_nexthop.py::test_InvalidNexthop PASSED                                                         [ 50%]
teamd/test_portchannel.py::test_PortChannel PASSED                                                              [100%]

============================================== 2 passed in 73.64 seconds ==============================================

- Description for the changelog

- A picture of a cute animal (not mandatory but encouraged)

[lguohan]

retest this please