configs: ls1046ardb: enable DM_SERIAL

As the serial devices are configured in the device tree, enable
DM_SERIAL in the ls1046ardb defconfigs.

Signed-off-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/configs/ls1046ardb_qspi_spl_defconfig b/configs/ls1046ardb_qspi_spl_defconfig
index 8f7d05f..eb0184c 100644
--- a/configs/ls1046ardb_qspi_spl_defconfig
+++ b/configs/ls1046ardb_qspi_spl_defconfig
@@ -118,7 +118,8 @@
 CONFIG_POWER_I2C=y
 CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH=y
 CONFIG_DM_SCSI=y
-CONFIG_SYS_NS16550_SERIAL=y
+CONFIG_DM_SERIAL=y
+CONFIG_SPL_SYS_NS16550_SERIAL=y
 CONFIG_SPI=y
 CONFIG_DM_SPI=y
 CONFIG_FSL_QSPI=y