remove some Makefile targets since they are obsolete under 4.20.y

patch/kernel/rockchip64-dev/general-add-overlay-compilation-support.patch

@@ -1,20 +1,3 @@
-diff --git a/arch/arm/Makefile b/arch/arm/Makefile
-index 65f4e2a4..9eb2043c 100644
---- a/arch/arm/Makefile
-+++ b/arch/arm/Makefile
-@@ -339,6 +339,12 @@ $(INSTALL_TARGETS):
- %.dtb: | scripts
- 	$(Q)$(MAKE) $(build)=$(boot)/dts MACHINE=$(MACHINE) $(boot)/dts/$@
-
-+%.dtbo: | scripts
-+	$(Q)$(MAKE) $(build)=$(boot)/dts MACHINE=$(MACHINE) $(boot)/dts/$@
-+
-+%.scr: | scripts
-+	$(Q)$(MAKE) $(build)=$(boot)/dts ARCH=$(ARCH) $(boot)/dts/$@
-+
- PHONY += dtbs dtbs_install
-
- dtbs: prepare scripts
 diff --git a/arch/arm/boot/.gitignore b/arch/arm/boot/.gitignore
 index 3c79f859..4e5c1d59 100644
 --- a/arch/arm/boot/.gitignore
@@ -25,24 +8,6 @@ index 3c79f859..4e5c1d59 100644
  uImage
 +*.dtb*
 +*.scr
-\ No newline at end of file
-diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
-index f839ecd9..9788f16d 100644
---- a/arch/arm64/Makefile
-+++ b/arch/arm64/Makefile
-@@ -121,6 +121,12 @@ zinstall install:
- %.dtb: scripts
- 	$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
-
-+%.dtbo: | scripts
-+	$(Q)$(MAKE) $(build)=$(boot)/dts MACHINE=$(MACHINE) $(boot)/dts/$@
-+
-+%.scr: | scripts
-+	$(Q)$(MAKE) $(build)=$(boot)/dts ARCH=$(ARCH) $(boot)/dts/$@
-+
- PHONY += dtbs dtbs_install
-
- dtbs: prepare scripts
 diff --git a/scripts/Makefile.dtbinst b/scripts/Makefile.dtbinst
 index 34614a48..8a8313d6 100644
 --- a/scripts/Makefile.dtbinst