board/ls1021aqds: Add DDR4 support

LS1021AQDS has a variant with DDR4 slot. This patch adds a new defconfig
for this variant to enable DDR4 support. RAW timing parameters are not
added for DDR4. The board timing parameters are only tuned for single-
rank 1600 and 1800MT/s with Micron DIMM 9ASF51272AZ-2G1A1 due to DIMM
availability.

Signed-off-by: York Sun <yorksun@freescale.com>
CC: Alison Wang <alison.wang@freescale.com>
diff --git a/arch/arm/include/asm/arch-ls102xa/config.h b/arch/arm/include/asm/arch-ls102xa/config.h
index ed78c33..a500b5b 100644
--- a/arch/arm/include/asm/arch-ls102xa/config.h
+++ b/arch/arm/include/asm/arch-ls102xa/config.h
@@ -50,7 +50,11 @@
 #ifdef CONFIG_DDR_SPD
 #define CONFIG_SYS_FSL_DDR_BE
 #define CONFIG_VERY_BIG_RAM
+#ifdef CONFIG_SYS_FSL_DDR4
+#define CONFIG_SYS_FSL_DDRC_GEN4
+#else
 #define CONFIG_SYS_FSL_DDRC_ARM_GEN3
+#endif
 #define CONFIG_SYS_FSL_DDR
 #define CONFIG_SYS_LS1_DDR_BLOCK1_SIZE		((phys_size_t)2 << 30)
 #define CONFIG_MAX_MEM_MAPPED			CONFIG_SYS_LS1_DDR_BLOCK1_SIZE
@@ -71,6 +75,7 @@
 #define CONFIG_MAX_CPUS				2
 #define CONFIG_SYS_FSL_IFC_BANK_COUNT		8
 #define CONFIG_NUM_DDR_CONTROLLERS		1
+#define CONFIG_SYS_FSL_DDR_VER			FSL_DDR_VER_5_0
 #else
 #error SoC not defined
 #endif