Arthur: update tf-sync-repos.sh

Signed-off-by: Arthur She <arthur.she@linaro.org>
Change-Id: I38c49ee4bdaa5a482b7871c834b4860beed4f961
diff --git a/ci/tf-sync-repos.sh b/ci/tf-sync-repos.sh
index e3ff622..447ecb1 100755
--- a/ci/tf-sync-repos.sh
+++ b/ci/tf-sync-repos.sh
@@ -53,3 +53,7 @@
 
 echo "Sync ${GERRIT_PROJECT}:${def_branch} to Github:${gh_default_branch}"
 git push --tags github ${def_branch}:${gh_default_branch}
+
+# Clean up workspace
+cd - > /dev/null
+rm -rf proj_src