ANDROID: ARM64: add option to build Image.gz/dtb combo

Allows a defconfig to set a list of dtbs to concatenate with an
Image.gz to create a Image.gz-dtb.

Includes 8adb162 arm64: Fix correct dtb clean-files location

Change-Id: I0b462322d5c970f1fdf37baffece7ad058099f4a
Signed-off-by: Alex Ray <aray@google.com>
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 2a79e2f..085f792 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -95,7 +95,12 @@
 core-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
 
 # Default target when executing plain make
+ifeq ($(CONFIG_BUILD_ARM64_APPENDED_DTB_IMAGE),y)
+KBUILD_IMAGE	:= Image.gz-dtb
+else
 KBUILD_IMAGE	:= Image.gz
+endif
+
 KBUILD_DTBS	:= dtbs
 
 all:	$(KBUILD_IMAGE) $(KBUILD_DTBS)
@@ -122,6 +127,9 @@
 dtbs_install:
 	$(Q)$(MAKE) $(dtbinst)=$(boot)/dts
 
+Image.gz-dtb: vmlinux scripts dtbs
+	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
+
 PHONY += vdso_install
 vdso_install:
 	$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso $@