arm: ls1021atwr: Enable driver model lpuart serial driver

Convert ls1021atwr_nor_lpuart to driver model support. As a start,
enable lpuart serial port driver.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Alison Wang <alison.wang@nxp.com>
Tested-by: Alison Wang <alison.wang@nxp.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index 5a6f75a..7706b41 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -93,7 +93,7 @@
 dtb-$(CONFIG_TARGET_STV0991) += stv0991.dtb
 
 dtb-$(CONFIG_LS102XA) += ls1021a-qds.dtb \
-	ls1021a-twr-duart.dtb
+	ls1021a-twr-duart.dtb ls1021a-twr-lpuart.dtb
 dtb-$(CONFIG_FSL_LSCH3) += fsl-ls2080a-qds.dtb \
 	fsl-ls2080a-rdb.dtb
 dtb-$(CONFIG_FSL_LSCH2) += fsl-ls1043a-qds.dtb \