numa: move large array from stack to _initdata section

  * Move large array "struct bootnode nodes" from stack to _initdata
    section to reduce amount of stack space required.

Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>