x86: fix ioapic bug again

un-revert:

 commit 4960c9df
 Author: Thomas Gleixner <tglx@linutronix.de>
 Date:   Tue Jan 22 10:23:01 2008 +0100

     Revert "x86: fix NMI watchdog & 'stopped time' problem"

         This reverts commit d4d25dec.

needs a proper fix though ...

Signed-off-by: Ingo Molnar <mingo@elte.hu>