armv7: Add support of ls1021a-iot board

The patch adds support for Freescale ls1021a-iot board.

Signed-off-by: Feng Li <feng.li_2@nxp.com>
[YS: rewrite commit message, fix whitespace in Kconfig]
Reviewed-by: York Sun <york.sun@nxp.com>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index 2c5b2f2..36133f5 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -143,7 +143,8 @@
 
 dtb-$(CONFIG_LS102XA) += ls1021a-qds-duart.dtb \
 	ls1021a-qds-lpuart.dtb \
-	ls1021a-twr-duart.dtb ls1021a-twr-lpuart.dtb
+	ls1021a-twr-duart.dtb ls1021a-twr-lpuart.dtb \
+	ls1021a-iot-duart.dtb
 dtb-$(CONFIG_FSL_LSCH3) += fsl-ls2080a-qds.dtb \
 	fsl-ls2080a-rdb.dtb
 dtb-$(CONFIG_FSL_LSCH2) += fsl-ls1043a-qds-duart.dtb \