kbuild: pkg: use -f $(srctree)/Makefile to recurse to top Makefile

'$(MAKE) KBUILD_SRC=' changes the working directory back and forth
between objtree and srctree.

It is better to recurse to the top-level Makefile directly.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

scripts/package/Makefile

@@ -59,7 +59,7 @@ rpm-pkg: FORCE
 # binrpm-pkg
 # ---------------------------------------------------------------------------
 binrpm-pkg: FORCE
-	$(MAKE) KBUILD_SRC=
+	$(MAKE) -f $(srctree)/Makefile
 	$(CONFIG_SHELL) $(MKSPEC) prebuilt > $(objtree)/binkernel.spec
 	+rpmbuild $(RPMOPTS) --define "_builddir $(objtree)" --target \
 		$(UTS_MACHINE) -bb $(objtree)/binkernel.spec
@@ -102,7 +102,7 @@ clean-dirs += $(objtree)/snap/
 # tarball targets
 # ---------------------------------------------------------------------------
 tar%pkg: FORCE
-	$(MAKE) KBUILD_SRC=
+	$(MAKE) -f $(srctree)/Makefile
 	$(CONFIG_SHELL) $(srctree)/scripts/package/buildtar $@
 
 clean-dirs += $(objtree)/tar-install/