BUG :  Allow axis = 'columns' with limit and no method to work on fillna. 
- [x] closes #40989
- [x] tests added / passed
- [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

Added an if-condition for when axis = 1 so as to transpose the result in pandas/tests/frame/methods/test_fillna.py, and created a test for this change. The test also tests for `inplace =True`. This solves issue #40989 
lgtm. @mzeitlin11 or @phofl if you'd take a quick look here. thanks @GYvan 