Fix warning:

In file included from include/asm/numa.h:5,
                 from arch/x86_64/kernel/setup64.c:27:
include/asm/numnodes.h:6:1: warning: "NODES_SHIFT" redefined
In file included from include/linux/mmzone.h:13,
                 from include/linux/gfp.h:4,
                 from include/linux/slab.h:15,
                 from include/linux/percpu.h:4,
                 from include/linux/sched.h:33,
                 from arch/x86_64/kernel/setup64.c:11:
include/linux/numa.h:11:1: warning: this is the location of the previous definition

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