powerpc/mpc8xxx: Enable 3-way and 4-way DDR interleaving

Restructure DDR interleaving option to support 3 and 4 DDR controllers
for 2-, 3- and 4-way interleaving.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>
diff --git a/arch/powerpc/cpu/mpc85xx/ddr-gen3.c b/arch/powerpc/cpu/mpc85xx/ddr-gen3.c
index 0761d70..ca4ed62 100644
--- a/arch/powerpc/cpu/mpc85xx/ddr-gen3.c
+++ b/arch/powerpc/cpu/mpc85xx/ddr-gen3.c
@@ -32,9 +32,21 @@
 	case 0:
 		ddr = (void *)CONFIG_SYS_MPC85xx_DDR_ADDR;
 		break;
+#if defined(CONFIG_SYS_MPC85xx_DDR2_ADDR) && (CONFIG_NUM_DDR_CONTROLLERS > 1)
 	case 1:
 		ddr = (void *)CONFIG_SYS_MPC85xx_DDR2_ADDR;
 		break;
+#endif
+#if defined(CONFIG_SYS_MPC85xx_DDR3_ADDR) && (CONFIG_NUM_DDR_CONTROLLERS > 2)
+	case 2:
+		ddr = (void *)CONFIG_SYS_MPC85xx_DDR3_ADDR;
+		break;
+#endif
+#if defined(CONFIG_SYS_MPC85xx_DDR4_ADDR) && (CONFIG_NUM_DDR_CONTROLLERS > 3)
+	case 3:
+		ddr = (void *)CONFIG_SYS_MPC85xx_DDR4_ADDR;
+		break;
+#endif
 	default:
 		printf("%s unexpected ctrl_num = %u\n", __FUNCTION__, ctrl_num);
 		return;