kbuild: buildtar: Remove unused $dirs

The shell variable $dirs is not used any more since 1fc9095846cc
("kbuild: tar-pkg: use tar rules in scripts/Makefile.package"),
therefore remove it".

Fixes: 1fc9095846cc ("kbuild: tar-pkg: use tar rules in scripts/Makefile.package")
Signed-off-by: Petr Vorel <[e-mail]>
Signed-off-by: Masahiro Yamada <[e-mail]>

scripts/package/buildtar

···
 #
 rm -rf -- "${tmpdir}"
 mkdir -p -- "${tmpdir}/boot"
-dirs=boot
 
 
 #
···
 #
 if grep -q '^CONFIG_MODULES=y' include/config/auto.conf; then
 	make ARCH="${ARCH}" -f ${srctree}/Makefile INSTALL_MOD_PATH="${tmpdir}" modules_install
-	dirs="$dirs lib"
 fi