mips: ath79: add AP121 reference board

This patch add board-level code and base DT for AP121.

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/board/qca/ap121/Kconfig b/board/qca/ap121/Kconfig
new file mode 100644
index 0000000..f7e768a
--- /dev/null
+++ b/board/qca/ap121/Kconfig
@@ -0,0 +1,12 @@
+if TARGET_AP121
+
+config SYS_VENDOR
+	default "qca"
+
+config SYS_BOARD
+	default "ap121"
+
+config SYS_CONFIG_NAME
+	default "ap121"
+
+endif