[202012][cherry-pick]Fix validation of input of config mirror_session add

[bingwang-ms]

Signed-off-by: bingwang [email protected]

What I did

This PR is to cherry-pick #2162 to 202012 branch after resolving conflict in test code.

FIX sonic-net/sonic-buildimage#10795

queue = 0 is not accepted by the validation of input because the follow check
https://github.com/Azure/sonic-utilities/blob/bce4694d3ad4454fc7181b99433457e76ab9e0a0/config/main.py#L2028-L2029

When addressing the issue, I saw similar issue in the logic of handling gre_type. The issue is also fixed.

How I did it

Change if queue to if queue is not None

How to verify it

Verified by UT

python setup.py test --addopts "tests/config_mirror_session_test.py -v" 
========================================================================================= test session starts =========================================================================================
collected 3 items                                                                                                                                                                                     

tests/config_mirror_session_test.py::test_mirror_session_add PASSED                                                                                                                             [ 33%]
tests/config_mirror_session_test.py::test_mirror_session_erspan_add PASSED                                                                                                                      [ 66%]
tests/config_mirror_session_test.py::test_mirror_session_span_add PASSED                                                                                                                        [100%]

========================================================================================== 3 passed in 0.96s ==========================================================================================

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)

[dprital]

@arfeigin , please review