x86: Disable AMD_NUMA for 32bit for now

Commit 2706a0bf

 ("x86, NUMA: Enable CONFIG_AMD_NUMA on 32bit
too") enabled AMD NUMA for 32bit too.  Unfortunately, SPARSEMEM
on 32bit had rather coarse (512MiB) addr->node mapping
granularity due to lack of space in page->flags.  This led to
boot failure on certain AMD NUMA machines which had 128MiB
alignment on nodes.

Patches to properly detect this condition and reject NUMA
configuration are posted[1] but deemed too pervasive for merge
at this point (-rc6).  Disable AMD NUMA for 32bit for now and
re-enable once the detection logic is merged.

[1] http://thread.gmane.org/gmane.linux.kernel/1161279/focus=1162583

Reported-by: Hans Rosenfeld <hans.rosenfeld@amd.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Conny Seidel <conny.seidel@amd.com>
Link: http://lkml.kernel.org/r/20110711083432.GC943@htj.dyndns.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>