Arthur: update ci/tf-sync-repos.sh

Signed-off-by: Arthur She <arthur.she@linaro.org>
Change-Id: Ia0965f7d3e2714e6761e4efede50157b170f28f4
diff --git a/ci/tf-sync-repos.sh b/ci/tf-sync-repos.sh
index 447ecb1..ce3c134 100755
--- a/ci/tf-sync-repos.sh
+++ b/ci/tf-sync-repos.sh
@@ -33,6 +33,8 @@
     exit 1
 fi
 
+cd ${WORKSPACE}
+
 gerrit_repo="https://review.trustedfirmware.org/${GERRIT_PROJECT}"
 echo "Cloning repository ${gerrit_repo}"
 git clone ${gerrit_repo} proj_src