arm64: Add dtbs target for building all the enabled dtb files

Based on Rob Herring's patches for arch/arm, this patch adds a dtbs
target to arch/arm64/boot/Makefile.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>

arch/arm64/Makefile

@@ -42,19 +42,23 @@ libs-y		+= $(LIBGCC)
 
 # Default target when executing plain make
 KBUILD_IMAGE	:= Image.gz
+KBUILD_DTBS	:= dtbs
 
-all:	$(KBUILD_IMAGE)
+all:	$(KBUILD_IMAGE) $(KBUILD_DTBS)
 
 boot := arch/arm64/boot
 
 Image Image.gz: vmlinux
-	$(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $(boot)/$@
+	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
 
 zinstall install: vmlinux
-	$(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $@
+	$(Q)$(MAKE) $(build)=$(boot) $@
 
-%.dtb:
-	$(Q)$(MAKE) $(build)=$(boot)/dts MACHINE=$(MACHINE) $(boot)/dts/$@
+%.dtb: scripts
+	$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
+
+dtbs: scripts
+	$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
 
 # We use MRPROPER_FILES and CLEAN_FILES now
 archclean:
@@ -63,6 +67,7 @@ archclean:
 define archhelp
   echo  '* Image.gz      - Compressed kernel image (arch/$(ARCH)/boot/Image.gz)'
   echo  '  Image         - Uncompressed kernel image (arch/$(ARCH)/boot/Image)'
+  echo  '* dtbs          - Build device tree blobs for enabled boards'
   echo  '  install       - Install uncompressed kernel'
   echo  '  zinstall      - Install compressed kernel'
   echo  '                  Install using (your) ~/bin/installkernel or'

arch/arm64/boot/dts/.gitignore

+*.dtb