mm: free folios in a batch in shrink_folio_list()

Use free_unref_page_batch() to free the folios.  This may increase the
number of IPIs from calling try_to_unmap_flush() more often, but that's
going to be very workload-dependent.  It may even reduce the number of
IPIs as we now batch-free large folios instead of freeing them one at a
time.

Link: https://lkml.kernel.org/r/20240227174254.710559-12-willy@infradead.org


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