[PATCH] ppc64: add memory present

Provide hooks for PPC64 to allow memory models to be informed of installed
memory areas.  This allows SPARSEMEM to instantiate mem_map for the populated
areas.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Martin Bligh <mbligh@aracnet.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>