powerpc/mpc8xxx: Enable calculation for fixed DDR chips

We used to have fixed parameters for soldered DDR chips. This patch
introduces CONFIG_SYS_DDR_RAW_TIMING to enable calculation based on timing
data from DDR chip datasheet, implemneted in board-specific files or header
files.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/cpu/mpc85xx/cpu.c b/arch/powerpc/cpu/mpc85xx/cpu.c
index f863f4a..53f0887 100644
--- a/arch/powerpc/cpu/mpc85xx/cpu.c
+++ b/arch/powerpc/cpu/mpc85xx/cpu.c
@@ -336,7 +336,9 @@
 	}
 #endif
 
-#if defined(CONFIG_SPD_EEPROM) || defined(CONFIG_DDR_SPD)
+#if	defined(CONFIG_SPD_EEPROM)	|| \
+	defined(CONFIG_DDR_SPD)		|| \
+	defined(CONFIG_SYS_DDR_RAW_TIMING)
 	dram_size = fsl_ddr_sdram();
 #else
 	dram_size = fixed_sdram();