arm: MediaTek: add basic support for MT7629 boards

This adds a general board file based on MT7629 SoCs from MediaTek.

Apart from the generic parts (cpu) we add some low level init codes
and initialize the early clocks.

Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/board/mediatek/mt7629/Makefile b/board/mediatek/mt7629/Makefile
new file mode 100644
index 0000000..83ccbba
--- /dev/null
+++ b/board/mediatek/mt7629/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier:	GPL-2.0
+
+obj-y += mt7629_rfb.o