x86: add check for node passed to node_to_cpumask, v3

  * When CONFIG_DEBUG_PER_CPU_MAPS is set, the node passed to
    node_to_cpumask and node_to_cpumask_ptr should be validated.
    If invalid, then a dump_stack is performed and a zero cpumask
    is returned.

v2: Slightly different version to remove a compiler warning.
v3: Redone to reflect moving setup.c -> setup_percpu.c

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: "akpm@linux-foundation.org" <akpm@linux-foundation.org>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>