[LLDP]Getting topology type to skip unsupported topology .

[chenkelly]

Description of PR

Summary:
Getting topology type to skip unsupported topology.

Type of change

• [] Bug fix
• [] Testbed and Framework(new/improvement)
• Test case(new/improvement)

Approach

How did you do it?

To follow #1468 solution

How did you verify/test it?

sonic@81f2fbf4efaf:~/sonic-mgmt/tests$ py.test --inventory=lab --host-pattern=2-9_ptf32  --module-path ../ansible/library/ --testbed=2-9_ptf32 --testbed_file=testbed.csv test_lldp.py --log-level=INFO -vvvv --show-capture=stdout --duration=0
 =============================================================================================== test session starts ===============================================================================================
 platform linux2 -- Python 2.7.12, pytest-4.6.7, py-1.8.0, pluggy-0.13.1 -- /usr/bin/python
 cachedir: .pytest_cache
 ansible: 2.8.7
 rootdir: /var/sonic/sonic-mgmt/tests, inifile: pytest.ini
 plugins: ansible-2.2.2, pyfakefs-3.7.1, csv-2.0.2
 collected 2 items   	

 test_lldp.py::test_lldp SKIPPED                                                                                                                                                                             [ 50%]
 test_lldp.py::test_lldp_neighbor SKIPPED                                                                                                                                                                    [100%]     	

 ============================================================================================= slowest test durations ==============================================================================================
 1.58s setup    test_lldp.py::test_lldp
 0.00s setup    test_lldp.py::test_lldp_neighbor
 0.00s teardown test_lldp.py::test_lldp_neighbor
 0.00s teardown test_lldp.py::test_lldp
 ============================================================================================ 2 skipped in 1.60 seconds ============================================================================================

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation