[multi asic] Change the test_dip_sip for multi asic platforms

[arlakshm]

Description of PR

Summary:
Fixes # (issue)

Type of change

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

Approach

What is the motivation for this PR?

Changes added to test_dip_sip to support multi asic platforms

How did you do it?

Change the test test_dip_sip to run on every ASIC connected to the external devices.

How did you verify/test it?

Run the test on single and multi asic platforms

• Single asic logs:

arlakshm@61e163aff932:/data/sonic-mgmt/tests$ cd ../tests;./run_tests.sh -n vms-kvm-t0 -d vlab01 -c ipfwd/test_dip_sip.py -f vtestbed.csv -i veos_vtb -u -e "--skip_sanity"
=== Running tests in groups ===
/usr/local/lib/python2.7/dist-packages/ansible/parsing/vault/__init__.py:44: CryptographyDeprecationWarning: Python 2 is no longer supported by the Python core team. Support for it is now deprecated in cryptography, and will be removed in a future release.
  from cryptography.exceptions import InvalidSignature
========================================================================== test session starts ==========================================================================platform linux2 -- Python 2.7.17, pytest-4.6.5, py-1.9.0, pluggy-0.13.1
ansible: 2.8.12
rootdir: /data/sonic-mgmt/tests, inifile: pytest.ini
plugins: forked-1.3.0, xdist-1.28.0, repeat-0.8.0, metadata-1.10.0, html-1.22.1, ansible-2.2.2
collected 1 item

ipfwd/test_dip_sip.py::test_dip_sip[vlab-01-None] PASSED                                                                                                          [100%]

-------------------------------------------------------- generated xml file: /data/sonic-mgmt/tests/logs/tr.xml ---------------------------------------------------------======================================================================= 1 passed in 32.22 seconds =======================================================================Exception AttributeError: "'NoneType' object has no attribute 'close'" in <bound method EventDescriptor.__del__ of <ptf.ptfutils.EventDescriptor instance at 0x7fb520217190>> ignored
arlakshm@61e163aff932:/data/sonic-mgmt/tests$

• Multi asic logs

Any platform specific information?

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

Documentation

[wangxin]

LGTM. @arlakshm, can you address the merge conflicts?