huge_memory: convert split_huge_page_to_list() to use a folio

Saves many calls to compound_head().

Link: https://lkml.kernel.org/r/20220902194653.1739778-53-willy@infradead.org


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