mm: add folio_is_pci_p2pdma()

mm: add folio_is_pci_p2pdma()

Reimplement is_pci_p2pdma_page() in terms of folio_is_pci_p2pdma().  Moves
the page_folio() call from inside page_pgmap() to is_pci_p2pdma_page().
This removes a page_folio() call from try_grab_folio() which already has a
folio and can pass it in.

Link: https://lkml.kernel.org/r/20250805172307.1302730-12-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>