sunxi: Use binman for sunxi boards

Move sunxi boards to use binman. This involves adding the image definition
to the device tree and using it in the Makefile.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/Makefile b/Makefile
index 7688e87..f5f82d2 100644
--- a/Makefile
+++ b/Makefile
@@ -1114,10 +1114,8 @@
 endif
 
 ifneq ($(CONFIG_ARCH_SUNXI),)
-OBJCOPYFLAGS_u-boot-sunxi-with-spl.bin = -I binary -O binary \
-				   --pad-to=$(CONFIG_SPL_PAD_TO) --gap-fill=0xff
-u-boot-sunxi-with-spl.bin: spl/sunxi-spl.bin u-boot.img FORCE
-	$(call if_changed,pad_cat)
+u-boot-sunxi-with-spl.bin: spl/sunxi-spl.bin u-boot.img u-boot.dtb FORCE
+	$(call if_changed,binman)
 endif
 
 ifneq ($(CONFIG_TEGRA),)