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/Kconfig b/board/mediatek/mt7629/Kconfig
new file mode 100644
index 0000000..6055164
--- /dev/null
+++ b/board/mediatek/mt7629/Kconfig
@@ -0,0 +1,17 @@
+if TARGET_MT7629
+
+config SYS_BOARD
+	default "mt7629"
+
+config SYS_CONFIG_NAME
+	default "mt7629"
+
+config MTK_SPL_PAD_SIZE
+	hex
+	default 0x10000
+
+config MTK_BROM_HEADER_INFO
+	string
+	default "media=nor"
+
+endif