dvbinfo/udp.c: pass on argument

The interface argument for udp_open was never passed on to the appropriate function.

examples/dvbinfo/udp.c

@@ -286,7 +286,7 @@ int udp_open(const char *interface, const char *ipaddress, int port)
 
         const struct sockaddr_storage *saddr = (const struct sockaddr_storage *)&ptr->ai_addr;
         if (is_multicast(saddr, ptr->ai_addrlen) &&
-            mcast_connect(s_ctl, NULL, saddr, ptr->ai_addrlen))
+            mcast_connect(s_ctl, interface, saddr, ptr->ai_addrlen))
         {
             close(s_ctl);
             s_ctl = -1;