MPC512x: factor out common code

Now that we have 3 boards for the MPC512x it turns out that they all
use the very same fixed_sdram() code.

This patch factors out this common code into cpu/mpc512x/fixed_sdram.c
and adds a new header file, include/asm-ppc/mpc512x.h, with some
macros, inline functions and prototype definitions specific to MPC512x
systems.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Stefan Roese <sr@denx.de>
Cc: Reinhard Arlt <reinhard.arlt@esd-electronics.com>
diff --git a/cpu/mpc512x/Makefile b/cpu/mpc512x/Makefile
index 022c676..427db7a 100644
--- a/cpu/mpc512x/Makefile
+++ b/cpu/mpc512x/Makefile
@@ -27,7 +27,15 @@
 LIB	= $(obj)lib$(CPU).a
 
 START	= start.o
-COBJS-y	:= traps.o cpu.o cpu_init.o speed.o interrupts.o serial.o i2c.o iopin.o
+COBJS-y	:= cpu.o
+COBJS-y	+= traps.o
+COBJS-y += cpu_init.o
+COBJS-y += fixed_sdram.o
+COBJS-y += i2c.o
+COBJS-y += interrupts.o
+COBJS-y += iopin.o
+COBJS-y += serial.o
+COBJS-y += speed.o
 COBJS-${CONFIG_FSL_DIU_FB} += diu.o
 COBJS-${CONFIG_FSL_DIU_FB} += ../../board/freescale/common/fsl_diu_fb.o
 COBJS-${CONFIG_FSL_DIU_FB} += ../../board/freescale/common/fsl_logo_bmp.o