[PATCH] x86_64: extra NODES_SHIFT definition

The generic linux/numa.h file defines NODES_SHIFT to 0 in case
the architecture did not.

Every architecture which has a NUMA config option defines
NODES_SHIFT in its asm-$ARCH headers, but only if NUMA is
enabled, except for x86_64.

This should make it like all the rest.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>