[PATCH] Fix up non-NUMA breakage in mmzone.h

If CONFIG_NUMA isn't set, we use the define in <linux/mmzone.h> for
early_pfn_to_nid (which defines it to 0).

Because of this, the prototype needs to move inside the CONFIG_NUMA too, or
anal gcc's get really confused.

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>