[PATCH] fix show_mem on discontig machines

[PATCH] fix show_mem on discontig machines

Dave Hansen recently did some bootmem and paging init cleanups, but I
missed this little bit when I tested his original patches.  We need to
initialize pgdat->node_mem_map correctly since a) we're using vmem_map, and
b) the core won't do it for us since we have a valid node_start_pfn I
believe.

Signed-off-by: Jesse Barnes <jbarnes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>