ARM: realview: build realview-dt SMP support only when used

The platsmp-dt.c file does not build when CONFIG_SMP is disabled:

platsmp-dt.c:84:2: error: unknown field 'smp_prepare_cpus' specified in initializer

This changes the Makefile to build it conditionally on CONFIG_SMP.
The legacy platsmp.c file is only used for ATAGS based builds, so
we can move it into the CONFIG_ATAGS conditional.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/mach-realview/Makefile

@@ -5,14 +5,16 @@ ccflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/$(src)/include \
 	-I$(srctree)/arch/arm/plat-versatile/include
 
 
-obj-$(CONFIG_REALVIEW_DT)		+= realview-dt.o platsmp-dt.o
+obj-$(CONFIG_REALVIEW_DT)		+= realview-dt.o
+obj-$(CONFIG_SMP)			+= platsmp-dt.o
 obj-y					:= core.o
+
 ifdef CONFIG_ATAGS
 obj-$(CONFIG_MACH_REALVIEW_EB)		+= realview_eb.o
 obj-$(CONFIG_MACH_REALVIEW_PB11MP)	+= realview_pb11mp.o
 obj-$(CONFIG_MACH_REALVIEW_PB1176)	+= realview_pb1176.o
 obj-$(CONFIG_MACH_REALVIEW_PBA8)	+= realview_pba8.o
 obj-$(CONFIG_MACH_REALVIEW_PBX)		+= realview_pbx.o
-endif
 obj-$(CONFIG_SMP)			+= platsmp.o
+endif
 obj-$(CONFIG_HOTPLUG_CPU)		+= hotplug.o