mm: remove rest of ACCESS_ONCE() usages

mm: remove rest of ACCESS_ONCE() usages

We converted some of the usages of ACCESS_ONCE to READ_ONCE in the mm/
tree since it doesn't work reliably on non-scalar types.

This patch removes the rest of the usages of ACCESS_ONCE, and use the new
READ_ONCE API for the read accesses.  This makes things cleaner, instead
of using separate/multiple sets of APIs.

Signed-off-by: Jason Low <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Acked-by: Davidlohr Bueso <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Reviewed-by: Christian Borntraeger <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>