mpc83xx: Get rid of CONFIG_SYS_DDR_BASE

CONFIG_SYS_DDR_BASE is specific to mpc83xx an is always set to the same
value as CONFIG_SYS_SDRAM_BASE. Just use CONFIG_SYS_SDRAM_BASE instead.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/include/configs/MPC837XERDB.h b/include/configs/MPC837XERDB.h
index ef23d00..33d4ced 100644
--- a/include/configs/MPC837XERDB.h
+++ b/include/configs/MPC837XERDB.h
@@ -58,9 +58,8 @@
 /*
  * DDR Setup
  */
-#define CONFIG_SYS_DDR_BASE		0x00000000 /* DDR is system memory */
-#define CONFIG_SYS_SDRAM_BASE		CONFIG_SYS_DDR_BASE
-#define CONFIG_SYS_DDR_SDRAM_BASE	CONFIG_SYS_DDR_BASE
+#define CONFIG_SYS_SDRAM_BASE		0x00000000 /* DDR is system memory */
+#define CONFIG_SYS_DDR_SDRAM_BASE	CONFIG_SYS_SDRAM_BASE
 #define CONFIG_SYS_DDR_SDRAM_CLK_CNTL	0x03000000
 #define CONFIG_SYS_83XX_DDR_USES_CS0