x86 - nmi merging procedure fixes/cleanups

Here are few pacthes over tip/x86/nmi

commit 3d1ba1da2b4ff4ace7801e99fb9a3095b182d847

Author: Ingo Molnar <[email protected]>
Date:   Mon Jun 2 13:50:10 2008 +0200

x86: fix nmi.c build bug

- fix incorrect nmi_watchdog assignment, clean the code a bit to eliminate a few #ifdef's
- code style cleanup/unification (seems to be _useless_ in functionallity since all checks are done by callers but you to decide)

Please give them good testing (for me it works well on both 32/64 modes but under QEMU)

- Cyrill -