x86: Cleanup hw_nmi.c cruft

The design of the hardlockup watchdog has changed and cruft was left
behind in the hw_nmi.c file.  Just remove the code that isn't used
anymore.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <1273266711-18706-7-git-send-email-dzickus@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>