lockup detector: Compile fixes from removing the old x86 nmi watchdog

My patch that removed the old x86 nmi watchdog broke other
arches.  This change reverts a piece of that patch and puts the
change in the correct spot.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: fweisbec@gmail.com
Cc: yinghai@kernel.org
LKML-Reference: <1291068437-5331-2-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>