kbuild: pkg: rename scripts/package/Makefile to scripts/Makefile.package

scripts/package/Makefile does not use $(obj) or $(src) at all.
It actually generates files and directories in the top of $(objtree).
I do not see much sense in descending into scripts/package/.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Makefile

@@ -1445,13 +1445,11 @@ distclean: mrproper
 
 # Packaging of the kernel to various formats
 # ---------------------------------------------------------------------------
-package-dir	:= scripts/package
 
 %src-pkg: FORCE
-	$(Q)$(MAKE) $(build)=$(package-dir) $@
+	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@
 %pkg: include/config/kernel.release FORCE
-	$(Q)$(MAKE) $(build)=$(package-dir) $@
-
+	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@
 
 # Brief documentation of the typical targets used
 # ---------------------------------------------------------------------------
@@ -1523,7 +1521,7 @@ help:
 	@echo '  or  "cd tools; make help"'
 	@echo  ''
 	@echo  'Kernel packaging:'
-	@$(MAKE) $(build)=$(package-dir) help
+	@$(MAKE) -f $(srctree)/scripts/Makefile.package help
 	@echo  ''
 	@echo  'Documentation targets:'
 	@$(MAKE) -f $(srctree)/Documentation/Makefile dochelp

scripts/package/Makefile → scripts/Makefile.package

 # SPDX-License-Identifier: GPL-2.0-only
 # Makefile for the different targets used to generate full packages of a kernel
-# It uses the generic clean infrastructure of kbuild
+
+include $(srctree)/scripts/Kbuild.include
 
 # RPM target
 # ---------------------------------------------------------------------------
@@ -154,3 +155,5 @@ help:
 	@echo '  perf-targz-src-pkg  - Build $(perf-tar).tar.gz source tarball'
 	@echo '  perf-tarbz2-src-pkg - Build $(perf-tar).tar.bz2 source tarball'
 	@echo '  perf-tarxz-src-pkg  - Build $(perf-tar).tar.xz source tarball'
+
+.PHONY: $(PHONY)