Add EV-iMX280-NANO-X-MB board

A simple prototyping board with one microSD port, one Ethernet port,
2 USB ports, I2C, SPI, GPIO, and UART interfaces.

Signed-off-by: Oleh Kravchenko <oleg@kaa.org.ua>
Cc: Stefano Babic <sbabic@denx.de>
diff --git a/MAINTAINERS b/MAINTAINERS
index 875eb5d..2accd1f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -923,9 +923,11 @@
 M:	Oleh Kravchenko <oleg@kaa.org.ua>
 S:	Maintained
 T:	git https://github.com/Oleh-Kravchenko/u-boot-out4.git
+F:	arch/arm/dts/ev-imx280-nano-x-mb.dts
 F:	arch/arm/dts/o4-imx-nano.dts
 F:	arch/arm/dts/o4-imx6ull-nano.dtsi
 F:	board/out4
+F:	configs/ev-imx280-nano-x-mb_defconfig
 F:	configs/o4-imx6ull-nano_defconfig
 F:	include/configs/o4-imx6ull-nano.h