mm: convert is_transparent_hugepage() to use a folio

Replace a use of page->compound_dtor with its folio equivalent.

Link: https://lkml.kernel.org/r/20230111142915.1001531-20-willy@infradead.org


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