mm: convert migrate_pages() to work on folios

Almost all of the callers & implementors of migrate_pages() were already
converted to use folios.  compaction_alloc() & compaction_free() are
trivial to convert a part of this patch and not worth splitting out.

Link: https://lkml.kernel.org/r/20230513001101.276972-1-willy@infradead.org


Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>