[PATCH] i386: Fix compilation with UP genericarch

Fix

arch/i386/mach-generic/built-in.o: In function `apicid_to_node':
summit.c:(.text+0x2f): undefined reference to `apicid_2_node'

with CONFIG_GENERICH_ARCH and !CONFIG_SMP
Signed-off-by: Andi Kleen <ak@suse.de>