Fix dual-master recipe adding missing parameter HTTPGerritMaster2Port

Fix an issue where HAProxy starts without the proper HTTP
port configured to reach Gerrit Master #2.

Change-Id: I33510d6154717e740d4035e79e094f1b360fcaa2
diff --git a/dual-master/Makefile b/dual-master/Makefile
index 4ae1edb..c9d67bf 100644
--- a/dual-master/Makefile
+++ b/dual-master/Makefile
@@ -87,6 +87,7 @@
 		ParameterKey=CertificateArn,ParameterValue=$(SSL_CERTIFICATE_ARN) \
 		ParameterKey=Subdomain,ParameterValue=$(LB_SUBDOMAIN) \
 		ParameterKey=HTTPGerritMaster1Port,ParameterValue=$(HTTP_HOST_PORT_MASTER1) \
+		ParameterKey=HTTPGerritMaster2Port,ParameterValue=$(HTTP_HOST_PORT_MASTER2) \
 		ParameterKey=SSHGerritMaster1Port,ParameterValue=$(SSH_HOST_PORT_MASTER1) \
 		ParameterKey=SSHGerritMaster2Port,ParameterValue=$(SSH_HOST_PORT_MASTER2) \
 		ParameterKey=HAProxyDockerImage,ParameterValue=aws-gerrit/haproxy:$(HAPROXY_HEAD_SHA1) \