TOOL-13555 disable syncing upstream with zfs master branch (#230)

Author: Prakash Surya

packages/zfs/config.sh

@@ -19,9 +19,6 @@
 DEFAULT_PACKAGE_GIT_URL="https://github.com/delphix/zfs.git"
 PACKAGE_DEPENDENCIES="@linux-kernel delphix-rust"
 
-UPSTREAM_GIT_URL="https://github.com/zfsonlinux/zfs.git"
-UPSTREAM_GIT_BRANCH="master"
-
 function prepare() {
 	logmust install_pkgs \
 		alien \
@@ -166,7 +163,3 @@ function build() {
 	logmust cd "$WORKDIR"
 	logmust mv "all-packages/"*.deb "artifacts/"
 }
-
-function update_upstream() {
-	logmust update_upstream_from_git
-}