Seems we are trying to init the node_mem_map when we don't need to, for
example when SPARSEMEM is enabled.  This causes the error below during
compilation.  Use CONFIG_FLAT_NODE_MEM_MAP to gate allocation and init.

  arch/x86_64/mm/numa.c: In function `setup_node_zones':
  arch/x86_64/mm/numa.c:191: error: structure has no member
                                                  named `node_mem_map'
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>