BUG-16807-1 SparseFrame fills with default_fill_value if data is None
- [ ] closes #16807
- [X] tests added / passed
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [X] whatsnew entry

Previously, the constructor for SparseFrame would default to `np.nan` if the data parameter was `None`, even if a `default_fill_value` is specified. This PR fixes this.