arm: mvebu: Add Allied Telesis x250 board

The x250 and SE250 are series of 10G L2+ switches from Allied Telesis.
There are a number of them in the range but as far as U-Boot is
concerned all the CPU block components are the same so there's only one
board defined.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index 042282f..6ad59ae 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -190,7 +190,8 @@
 	cn9130-crb-A.dtb			\
 	cn9130-crb-B.dtb			\
 	ac5-98dx35xx-rd.dtb			\
-	ac5-98dx35xx-atl-x240.dtb
+	ac5-98dx35xx-atl-x240.dtb		\
+	cn9130-atl-x250.dtb
 endif
 
 dtb-$(CONFIG_ARCH_SYNQUACER) += synquacer-sc2a11-developerbox.dtb