To skip LLDP pytest on ptf32 and ptf64 topology.

[chenkelly]

Description of PR

The ptf32 and ptf64 topology don't use VMs which run LLDP.
DUT will not get any LLDP neighbor and test case will fail due to LLDP neighbor checking.
According to testcases.yml, lldp don't support on ptf32 and ptf64 topology.
To check topology and then skip LLDP pytest on ptf32 and ptf64 topology.

Summary:
Fixes # (issue)

Type of change

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

Approach

How did you do it?

To skip LLDP pytest on ptf32 and ptf64 topology.

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