Makefile: sunxi: Don't use binman to build ATF image

At present with sunxi 64-bit, the Makefile builds
u-boot-sunxi-with-spl.bin and then binman overwrites it with its own
version. But the binman definition lacks some parts, in particular
BL31.

For now, work around this with a hack.

Tested-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Simon Glass <sjg@chromium.org>
Fixes: 42b18df80fd ("x86: Makefile: Drop explicit targets built by binman")
diff --git a/Makefile b/Makefile
index 2629a74..4483a9b 100644
--- a/Makefile
+++ b/Makefile
@@ -1024,9 +1024,13 @@
 inputs: $(INPUTS-y)
 
 all: .binman_stamp inputs
+	# Hack for sunxi which doesn't have a proper binman definition for
+	# 64-bit boards
+ifneq ($(CONFIG_ARCH_SUNXI)$(CONFIG_ARM64),yy)
 ifeq ($(CONFIG_BINMAN),y)
 	$(call if_changed,binman)
 endif
+endif
 
 # Timestamp file to make sure that binman always runs
 .binman_stamp: FORCE