Pylint no-member warnings in 4.5.4.58

### Expected behaviour



Pylint was previously able to inspect `cv2` member existence with the `extension-pkg-whitelist` parameter.



### Actual behaviour



For opencv-python-4.5.4.58, pylint can no longer inspect the members.



### Steps to reproduce



On Windows 10, Python 3.8 64bit, using Pylint 2.11.1:



```py

"""Test module test.py"""

from cv2 import getStructuringElement, MORPH_ELLIPSE



a = getStructuringElement(MORPH_ELLIPSE, (3, 3))

```



With opencv-python-4.5.3.56:



```

$ pylint test.py --extension-pkg-whitelist=cv2



-------------------------------------------------------------------

Your code has been rated at 10.00/10 (previous run: 5.00/10, +5.00)

```



With opencv-python-4.5.4.58:



```

$ pylint test.py --extension-pkg-whitelist=cv2

************* Module test

test.py:2:0: E0611: No name 'getStructuringElement' in module 'cv2' (no-name-in-module)

test.py:2:0: E0611: No name 'MORPH_ELLIPSE' in module 'cv2' (no-name-in-module)



----------------------------------------------------------------------

Your code has been rated at -40.00/10 (previous run: 10.00/10, -50.00)

```



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