i386: fix NMI watchdog not reserving its MSRs

At system boot time, the NMI watchdog no longer reserved its MSRs, allowing
other subsystems to mess with them.  Fix that.

Signed-off-by: Björn Steinbrink <B.Steinbrink@gmx.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>