nds32: Support AE3XX platform.

Support Andestech AE3xx platform: serial, timer device tree flow.

Signed-off-by: rick <rick@andestech.com>
diff --git a/arch/nds32/dts/Makefile b/arch/nds32/dts/Makefile
index 2d8480b..1d6b195 100644
--- a/arch/nds32/dts/Makefile
+++ b/arch/nds32/dts/Makefile
@@ -3,6 +3,7 @@
 #
 
 dtb-$(CONFIG_TARGET_ADP_AG101P) += ag101p.dtb
+dtb-$(CONFIG_TARGET_ADP_AE3XX) += ae3xx.dtb
 targets += $(dtb-y)
 
 DTC_FLAGS += -R 4 -p 0x1000