mm, dax: convert vmf_insert_pfn_pmd() to pfn_t

Similar to the conversion of vm_insert_mixed() use pfn_t in the
vmf_insert_pfn_pmd() to tag the resulting pte with _PAGE_DEVICE when the
pfn is backed by a devm_memremap_pages() mapping.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/dax.c b/fs/dax.c
index 574763e..96ac307 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -693,7 +693,7 @@
 		dax_unmap_atomic(bdev, &dax);
 
 		result |= vmf_insert_pfn_pmd(vma, address, pmd,
-				pfn_t_to_pfn(dax.pfn), write);
+				dax.pfn, write);
 	}
 
  out: