This allows the cast in lowmem_page_address (introduced as a warning fixup to
33dd4e0ec911 "mm: make some struct page's const") to be removed.
Propagate const'ness to page_to_section() as well since it is required by
__page_to_pfn.
Signed-off-by: Ian Campbell<ian.campbell@xxxxxxxxxx>
Cc: Andrea Arcangeli<aarcange@xxxxxxxxxx>
Cc: Rik van Riel<riel@xxxxxxxxxx>
Cc: Michel Lespinasse<walken@xxxxxxxxxx>
Cc: Mel Gorman<mel@xxxxxxxxx>
Cc: Andrew Morton<akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds<torvalds@xxxxxxxxxxxxxxxxxxxx>