mm: remove try_to_free_swap()

All callers have now been converted to folio_free_swap() and we can remove
this wrapper.

Link: https://lkml.kernel.org/r/20220902194653.1739778-49-willy@infradead.org


Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>