ARM: mvebu: rename armada-385-amc.dts to armada-385-db-88f6820-amc.dts

This board was added to u-boot first but the Linux maintainers requested
a more descriptive name. Rename the file to match the Linux usage and
update the board defconfig.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index 524c1ee..0bed99b 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -138,7 +138,7 @@
 	armada-388-clearfog.dtb			\
 	armada-388-gp.dtb			\
 	armada-388-helios4.dtb			\
-	armada-385-amc.dtb			\
+	armada-385-db-88f6820-amc.dtb		\
 	armada-385-turris-omnia.dtb		\
 	armada-7040-db.dtb			\
 	armada-7040-db-nand.dtb			\