ls102xa: ddr4: Use LPUART as console output to verify DCU driver

On QDS board with DDR4 DIMM, LPUART is used as console
output to verify DCU driver. This patch adds
ls1021aqds_ddr4_nor_lpuart_defconfig for this support.
Signed-off-by: NAlison Wang <alison.wang@freescale.com>
Reviewed-by: NYork Sun <yorksun@freescale.com>

board/freescale/ls1021aqds/MAINTAINERS

@@ -5,6 +5,7 @@ F:	board/freescale/ls1021aqds/
 F:	include/configs/ls1021aqds.h
 F:	configs/ls1021aqds_nor_defconfig
 F:	configs/ls1021aqds_ddr4_nor_defconfig
+F:	configs/ls1021aqds_ddr4_nor_lpuart_defconfig
 F:	configs/ls1021aqds_nor_SECURE_BOOT_defconfig
 F:	configs/ls1021aqds_nor_lpuart_defconfig
 F:	configs/ls1021aqds_sdcard_defconfig

configs/ls1021aqds_ddr4_nor_lpuart_defconfig

+CONFIG_SYS_EXTRA_OPTIONS="SYS_FSL_DDR4,LPUART"
+CONFIG_ARM=y
+CONFIG_TARGET_LS1021AQDS=y