x86, xenoprof: Add Nehalem to list of ppro cores

x86, xenoprof: Add Nehalem to list of ppro cores

Straight port from Linus's tree:

commit 4b9f12a3779c548b68bc9af7d94030868ad3aa1b
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu Jul 24 17:29:00 2008 -0700

    x86/oprofile/nmi_int: add Nehalem to list of ppro cores

    ..otherwise oprofile will fall back on that poor timer interrupt.

    Also replace the unreadable chain of if-statements with a
    "switch()"
    statement instead. It generates better code, and is a lot clearer.

    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>