Only run android-dtb for arm64

Author: gsingh93

Makefile

@@ -492,8 +492,11 @@ ANDROID_DTB := $(OUT_DIR)/android.dtb
 QEMU_DTB := $(OUT_DIR)/qemu.dtb
 QEMU_DTS := $(OUT_DIR)/qemu.dts
 
-.PHONY: android_dtb
+.PHONY: android-dtb
 android-dtb $(ANDROID_DTB):
+ifneq ($(ARCH),arm64)
+   $(error android-dtb is only supported from arm64)
+endif
 	QEMU_EXTRA_ARGS="-M dumpdtb=$(QEMU_DTB)" $(MAKE) run
 	$(DTC) -I dtb -O dts $(QEMU_DTB) > $(QEMU_DTS)
 	cat $(QEMU_DTS) $(ATF_DIR)/firmware.android.dts > $(ANDROID_DTS)