ARM: sunxi: Build u-boot-sunxi-with-spl.bin on ARM64 as well

In README.sunxi64 we tell the user how to optionally create
u-boot-sunxi-with-spl.bin by manually running cat. Instead, have the
build system create the file automatically just like it does for 32-bit
sunxi boards.

Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
diff --git a/Makefile b/Makefile
index 2d825b9..5fa1478 100644
--- a/Makefile
+++ b/Makefile
@@ -1191,8 +1191,13 @@
 endif
 
 ifneq ($(CONFIG_ARCH_SUNXI),)
+ifeq ($(CONFIG_ARM64),)
 u-boot-sunxi-with-spl.bin: spl/sunxi-spl.bin u-boot.img u-boot.dtb FORCE
 	$(call if_changed,binman)
+else
+u-boot-sunxi-with-spl.bin: spl/sunxi-spl.bin u-boot.itb FORCE
+	$(call if_changed,cat)
+endif
 endif
 
 ifneq ($(CONFIG_TEGRA),)