Avoid reassign vars

Change-Id: I3b8eb39aa6b297b2f3ea83807e8581f031d58a09

manifests/gateway/static.pp

@@ -92,7 +92,7 @@ class midonet::gateway::static (
   $scripts_dir             = '/tmp',
   $uplink_script           = 'create_fake_uplink_l2.sh',
   $ensure_scripts          = 'present',
-  $hostname                = $::hostname,
+  $myhostname              = $::hostname,
   $masquerade              = 'on'
 ) {
 

templates/gateway/create_fake_uplink_l2.sh.erb

@@ -23,7 +23,7 @@ EDGE_ROUTER=<%= @edge_router %>
 VETH0_IP=<%= @veth0_ip %>
 VETH1_IP=<%= @veth1_ip %>
 VETH_NETWORK=<%= @veth_network %>
-HOSTNAME=<%= @hostname %>
+HOSTNAME=<%= @myhostname %>
 MASQUERADE_ON=<%= @masquerade %>
 
 HOST_ID=$(midonet-cli -A -e host list | grep ${HOSTNAME} | awk '{ print $2 }')