[POWERPC] PS3: Fix uniprocessor kernel build

Allow to build a uniprocessor kernel for PS3.
Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/ps3/Makefile

-obj-y += setup.o mm.o smp.o time.o hvcall.o htab.o repository.o
+obj-y += setup.o mm.o time.o hvcall.o htab.o repository.o
 obj-y += interrupt.o exports.o os-area.o
 
+obj-$(CONFIG_SMP) += smp.o
 obj-$(CONFIG_SPU_BASE) += spu.o