LB/Binding: fix HAproxy binding IPs

This patch fixes a bug introduced in the last pull request with HA
refacto.

Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>

manifests/loadbalancer/binding.pp

@@ -56,7 +56,7 @@ define cloud::loadbalancer::binding (
     cloud::loadbalancer::listen_http { $name :
       ports     => $port,
       httpchk   => $httpchk,
-      listen_ip => [$listen_ip_real];
+      listen_ip => $listen_ip_real;
     }
   }