board/seco: Add mx6q-uq7 basic board support

Add basic SECO MX6Q/uQ7 board support (Ethernet, UART, SD are supported).
It also adds a Kconfig skeleton to later add more SECO board (supporting
SoC and board variants).

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
diff --git a/board/seco/mx6quq7/MAINTAINERS b/board/seco/mx6quq7/MAINTAINERS
new file mode 100644
index 0000000..60fd4ca
--- /dev/null
+++ b/board/seco/mx6quq7/MAINTAINERS
@@ -0,0 +1,6 @@
+MX6QUQ7 BOARD
+M:	Boris Brezillon <boris.brezillon@free-electrons.com>
+S:	Maintained
+F:	board/seco/mx6quq7/
+F:	include/configs/secomx6quq7.h
+F:	configs/secomx6quq7_defconfig