x86: fix nodemap_size according to nodeid bits

memnode.map is s16 array because of nodeid is 16 bit now.

so need to increase the nodemap_size according to that bits.

Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>