csky: dtb Kbuild fixup patches for linux-4.20-rc1

These patches are complementary to "C-SKY(csky) Port for Linux 4.20" and
 fixup dtb Kbuild to follow the new Devicetree dtb build rules.
 
 Link: https://lore.kernel.org/lkml/CABGGisxiWaQn9qDqpfxEWcckkGJfMzFvSPGvuhQK7oB404-6DQ@mail.gmail.com/
 Signed-off-by: Guo Ren <ren_guo@c-sky.com>
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Merge tag 'csky-for-linus-4.20-fixup-dtb' of https://github.com/c-sky/csky-linux

Pull csky dtb fixups from Guo Ren:
 "These fix the csky dtb Kbuild to follow the new Devicetree dtb build
  rules"

* tag 'csky-for-linus-4.20-fixup-dtb' of https://github.com/c-sky/csky-linux:
  csky: use common dtb build rules
  csky: remove builtin-dtb Kbuild

arch/csky/Kconfig.debug

@@ -1,9 +1 @@
-menu "C-SKY Debug Options"
-config CSKY_BUILTIN_DTB
-	string "Use kernel builtin dtb"
-	help
-	  User could define the dtb instead of the one which is passed from
-	  bootloader.
-	  Sometimes for debug, we want to use a built-in dtb and then we needn't
-	  modify bootloader at all.
-endmenu
+# dummy file, do not delete

arch/csky/Makefile

@@ -65,26 +65,15 @@ libs-y += arch/csky/lib/ \
 	$(shell $(CC) $(KBUILD_CFLAGS) $(KCFLAGS) -print-libgcc-file-name)
 
 boot := arch/csky/boot
-ifneq '$(CONFIG_CSKY_BUILTIN_DTB)' '""'
 core-y += $(boot)/dts/
-endif
 
 all: zImage
 
-
-dtbs: scripts
-	$(Q)$(MAKE) $(build)=$(boot)/dts
-
-%.dtb %.dtb.S %.dtb.o: scripts
-	$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
-
-zImage Image uImage: vmlinux dtbs
+zImage Image uImage: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
 
 archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)
-	$(Q)$(MAKE) $(clean)=$(boot)/dts
-	rm -rf arch/csky/include/generated
 
 define archhelp
   echo  '* zImage       - Compressed kernel image (arch/$(ARCH)/boot/zImage)'

arch/csky/boot/dts/Makefile

@@ -1,13 +1,3 @@
 dtstree	:= $(srctree)/$(src)
 
-ifneq '$(CONFIG_CSKY_BUILTIN_DTB)' '""'
-builtindtb-y := $(patsubst "%",%,$(CONFIG_CSKY_BUILTIN_DTB))
-dtb-y += $(builtindtb-y).dtb
-obj-y += $(builtindtb-y).dtb.o
-.SECONDARY: $(obj)/$(builtindtb-y).dtb.S
-else
 dtb-y := $(patsubst $(dtstree)/%.dts,%.dtb, $(wildcard $(dtstree)/*.dts))
-endif
-
-always += $(dtb-y)
-clean-files += *.dtb *.dtb.S