Revert "[POWERPC] Fake NUMA emulation for PowerPC"

This reverts commit 5c3f5892

,
basically because it changes behaviour even when no fake NUMA
information is specified on the kernel command line.

Firstly, it changes the nid, thus destroying the real NUMA
information.  Secondly, it also changes behaviour in that if a node
ends up with no memory in it because of the memory limit, we used to
set it online and now we don't.

Also, in the non-NUMA case with no fake NUMA information, we do
node_set_online once for each LMB now, whereas previously we only did
it once.  I don't know if that is actually a problem, but it does seem
unnecessary.

Signed-off-by: Paul Mackerras <paulus@samba.org>