mm, dax, gpu: convert vm_insert_mixed to pfn_t

Convert the raw unsigned long 'pfn' argument to pfn_t for the purpose of
evaluating the PFN_MAP and PFN_DEV flags.  When both are set it triggers
_PAGE_DEVMAP to be set in the resulting pte.

There are no functional changes to the gpu drivers as a result of this
conversion.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: David Airlie <airlied@linux.ie>
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 6b13d6c..574763e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -363,7 +363,7 @@
 	}
 	dax_unmap_atomic(bdev, &dax);
 
-	error = vm_insert_mixed(vma, vaddr, pfn_t_to_pfn(dax.pfn));
+	error = vm_insert_mixed(vma, vaddr, dax.pfn);
 
  out:
 	i_mmap_unlock_read(mapping);