Rename _PFN_SHIFT to PFN_PTE_SHIFT.  Convert a few places
to call set_pte() instead of set_pte_at().  Add set_ptes(),
update_mmu_cache_range(), flush_icache_pages() and flush_dcache_folio().
Change the PG_arch_1 (aka PG_dcache_dirty) flag from being per-page
to per-folio.

Link: https://lkml.kernel.org/r/20230802151406.3735276-18-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>