SPL: Port SPL framework to powerpc

This patch enables the SPL framework to be used on powerpc platforms
and not only ARM.

timer_init() does not exist on PPC systems. The timer (decrementer) is
initialized and enabled in interrupt_init() here. And currently
interrupt_init() is called after relocation to SDRAM. Since the only
powerpc SPL implementation (a3m071) doesn't need a timer, let's remove
this timer_init() call for PPC systems.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 20c5c38..bf40676 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -79,6 +79,10 @@
 
 endif # not minimal
 
+ifdef CONFIG_SPL_BUILD
+COBJS-$(CONFIG_SPL_FRAMEWORK) += spl.o
+endif
+
 COBJS	+= $(sort $(COBJS-y))
 
 SRCS	:= $(GLSOBJS:.o=.S) $(GLCOBJS:.o=.c) \