[PATCH] ppc64: Updated Olof misc updates 3/3

Replace some of the hard-coded constants with PAGE_SIZE/SHIFT/ORDER where
appropriate.

Likewise, in a couple of places it doesn't make sense to base some
allocations on page size when all that's required is a constant 4K,
etc.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>