sunxi: binman: Respect the default FIT configuration

binman can fill in the default FIT configuration index as selected by
the "default-dt" argument, which is set to CONFIG_DEFAULT_DEVICE_TREE.
Let's respect the user's configuration by taking advantage of this
feature, instead of always defaulting to the first device tree in
CONFIG_OF_LIST.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/arch/arm/dts/sunxi-u-boot.dtsi b/arch/arm/dts/sunxi-u-boot.dtsi
index cd096bf..f822588 100644
--- a/arch/arm/dts/sunxi-u-boot.dtsi
+++ b/arch/arm/dts/sunxi-u-boot.dtsi
@@ -86,7 +86,7 @@
 			};
 
 			configurations {
-				default = "config-1";
+				default = "@config-DEFAULT-SEQ";
 
 				@config-SEQ {
 					description = "NAME";