From: Philippe Elie <phil.el@wanadoo.fr>

With nmi_watchdog=2 and a P4 ht box the nmi is occurring only on logical
processor 0, it's better to get it on both.

With this patch, on x86 SMP and nmi_watchdog=2, nmi interupts occur at 1000
hz (if the cpu is loaded) not at the intended 1 hz rate but that's a distinct
problem.