Fix ubuntu_docker_mtu_fix() function

Do not translate vaiables. Pass the text as is

Change-Id: I05b5c33ec79191dd4959ac10b0ac1d13c2973078
Issue-ID: CIMAN-118
Signed-off-by: Jessica Wagantall <jwagantall@linuxfoundation.org>
diff --git a/packer/provision/docker.sh b/packer/provision/docker.sh
index 12ebfc0..9d34eb0 100644
--- a/packer/provision/docker.sh
+++ b/packer/provision/docker.sh
@@ -32,7 +32,7 @@
 ubuntu_docker_mtu_fix(){
     echo "---> Fixing docker's mtu settings"
     systemctl stop docker
-    cat <<EOL > /etc/systemd/system/docker.service
+    cat <<'EOL' > /etc/systemd/system/docker.service
 [Unit]
 Description=Docker Application Container Engine
 Documentation=https://docs.docker.com