[PATCH] x86_64: Remove useless KDB vector

It was set as an NMI, but the NMI bit always forces an interrupt
to end up at vector 2. So it was never used. Remove.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>