kbuild: deb-pkg: remove the fakeroot builds support

In 2017, the dpkg suite introduced the rootless builds support with the
following commits:

  - 2436807c87b0 ("dpkg-deb: Add support for rootless builds")
  - fca1bfe84068 ("dpkg-buildpackage: Add support for rootless builds")

This feature is available in the default dpkg on Debian 10 and Ubuntu
20.04.

Remove the old method.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/package/builddeb

@@ -36,19 +36,13 @@ create_package() {
 	sh -c "cd '$pdir'; find . -type f ! -path './DEBIAN/*' -printf '%P\0' \
 		| xargs -r0 md5sum > DEBIAN/md5sums"
 
-	# Fix ownership and permissions
-	if [ "$DEB_RULES_REQUIRES_ROOT" = "no" ]; then
-		dpkg_deb_opts="--root-owner-group"
-	else
-		chown -R root:root "$pdir"
-	fi
 	# a+rX in case we are in a restrictive umask environment like 0077
 	# ug-s in case we build in a setuid/setgid directory
 	chmod -R go-w,a+rX,ug-s "$pdir"
 
 	# Create the package
 	dpkg-gencontrol -p$pname -P"$pdir"
-	dpkg-deb $dpkg_deb_opts ${KDEB_COMPRESS:+-Z$KDEB_COMPRESS} --build "$pdir" ..
+	dpkg-deb --root-owner-group ${KDEB_COMPRESS:+-Z$KDEB_COMPRESS} --build "$pdir" ..
 }
 
 install_linux_image () {