powerpc, 8xx: move immap.c in arch/powerpc/cpu/mpc8xx/

immap.c used to be common to several CPUs. It is now
only linked to the 8xx, so this patch moves it into
arch/powerpc/cpu/mpc8xx/

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Heiko Schocher <hs@denx.de>
diff --git a/arch/powerpc/cpu/mpc8xx/Makefile b/arch/powerpc/cpu/mpc8xx/Makefile
index 5dd801d..eae02da 100644
--- a/arch/powerpc/cpu/mpc8xx/Makefile
+++ b/arch/powerpc/cpu/mpc8xx/Makefile
@@ -11,6 +11,7 @@
 obj-y	+= cpu_init.o
 obj-y	+= fec.o
 obj-$(CONFIG_OF_LIBFDT) += fdt.o
+obj-$(CONFIG_CMD_IMMAP) += immap.o
 obj-y	+= interrupts.o
 obj-y	+= serial.o
 obj-y	+= speed.o