The few folios which can't be moved to the LRU list (because their
refcount dropped to zero) used to be returned to the caller to dispose of.
Make this simpler to call by freeing the folios directly through
free_unref_folios().

Link: https://lkml.kernel.org/r/20240227174254.710559-13-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>