BUG: Fix series clipping NA issue
Series clipping method could not handle series with NA values.
Issue was fixed by first comparing values and only after then converted
to numpy array. Now the test code provided with the issue ticket provides an expected result.

- [x] closes #40581
- [x] tests added / passed
 - I did run test_fast.sh and 3 test failed but I think they are not related to my changes
   -  test_can_set_locale_valid_set 
   -  test_header_multi_index_blank_line[c_high]
   - test_header_multi_index_blank_line[c_high]
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [x] whatsnew entry


Hello @Rasori! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:





There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2021-04-28 18:17:50 UTC The test fail is not related to my changes.

E: I re-pushed the changes to see if the check passes this time. At least checks of other PRs are passing ... thanks @Rasori  This seemed to cause a performance regression. https://pandas.pydata.org/speed/pandas/index.html#series_methods.Clip.time_clip?python=3.8&Cython=0.29.21&p-n=50&commits=29512dc9ea2b066ab5f4a7cb80c1f8f5becef1c2 @TomAugspurger if u wouldn't mind creating a new issue about this perf regression