Add PFN_PTE_SHIFT, update_mmu_cache_range() and flush_dcache_folio(). 
Change the PG_arch_1 (aka PG_dcache_clean) flag from being per-page to
per-folio, which makes arch_dma_mark_clean() and mark_clean() a little
more exciting.

[willy@infradead.org: fix folio_size() handling]
  Link: https://lkml.kernel.org/r/ZNPlOCe8F+nrzPxr@casper.infradead.org
Link: https://lkml.kernel.org/r/20230802151406.3735276-14-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>