[POWERPC] Fake NUMA emulation for PowerPC

Here's a dumb simple implementation of fake NUMA nodes for PowerPC.
Fake NUMA nodes can be specified using the following command line
option

numa=fake=<node range>

node range is of the format <range1>,<range2>,...<rangeN>

Each of the rangeX parameters is passed using memparse().  I find the
patch useful for fake NUMA emulation on my simple PowerPC machine.
I've tested it on a numa box with the following arguments

numa=fake=512M
numa=fake=512M,768M
numa=fake=256M,512M mem=512M
numa=fake=1G mem=768M
numa=fake=
without any numa= argument

The other side-effect introduced by this patch is that; in the case
where we don't have NUMA information, we now set a node online after
adding each LMB.  This node could very well be node 0, but in the case
that we enable fake NUMA nodes, when we cross node boundaries, we need
to set the new node online.

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>