mips: ath79: add AP143 reference board

This patch add board-level code and base DT for AP143.

Signed-off-by: Wills Wang <wills.wang@live.com>
[updated defconfig, enabled CONFIG_USE_PRIVATE_LIBGCC=y]
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
diff --git a/arch/mips/dts/Makefile b/arch/mips/dts/Makefile
index 30e5c68..bd87ead 100644
--- a/arch/mips/dts/Makefile
+++ b/arch/mips/dts/Makefile
@@ -3,6 +3,7 @@
 #
 
 dtb-$(CONFIG_TARGET_AP121) += ap121.dtb
+dtb-$(CONFIG_TARGET_AP143) += ap143.dtb
 dtb-$(CONFIG_TARGET_PIC32MZDASK) += pic32mzda_sk.dtb
 
 targets += $(dtb-y)