debian: fix XMPP modules build

Many thanks to Nick Altmann for reporting it

Author: razvancrainea

packaging/debian/rules

@@ -270,7 +270,7 @@ XMLRPC_MODULES = mi_xmlrpc_ng
 XMLRPC_MOD_PATH=$(addprefix modules/, $(XMLRPC_MODULES))
 XMPP_PKGNAME = opensips-xmpp-module
 XMPP_MODULES = xmpp
-XMPP_MOD_PATH=$(addprefix modules/, $(IPSEC_MODULES))
+XMPP_MOD_PATH=$(addprefix modules/, $(XMPP_MODULES))
 IPSEC_PKGNAME = opensips-ipsec-module
 IPSEC_MODULES = proto_ipsec
 IPSEC_MOD_PATH=$(addprefix modules/, $(IPSEC_MODULES))