[mgcp] Ignore every dummy packet...

This routine should operate on different packets and the
dummy load is smaller than a legitimate RTP header so it
is unlikely we will filture out genuine traffic.

The reason is the dummy load might be send more than once.
diff --git a/openbsc/src/mgcp/mgcp_network.c b/openbsc/src/mgcp/mgcp_network.c
index 49d21be..73356f7 100644
--- a/openbsc/src/mgcp/mgcp_network.c
+++ b/openbsc/src/mgcp/mgcp_network.c
@@ -172,16 +172,16 @@
 				ENDPOINT_NUMBER(endp), ntohs(endp->bts_rtp), ntohs(endp->bts_rtcp),
 				inet_ntoa(addr.sin_addr));
 
-			/* throw away dummy message */
-			if (rc == 1 && buf[0] == DUMMY_LOAD) {
-				LOGP(DMGCP, LOGL_NOTICE, "Filtered dummy on 0x%x\n",
-				     ENDPOINT_NUMBER(endp));
-				return 0;
-			}
-
 		}
 	}
 
+	/* throw away dummy message */
+	if (rc == 1 && buf[0] == DUMMY_LOAD) {
+		LOGP(DMGCP, LOGL_NOTICE, "Filtered dummy on 0x%x\n",
+			ENDPOINT_NUMBER(endp));
+		return 0;
+	}
+
 	/* do this before the loop handling */
 	if (dest == DEST_NETWORK)
 		++endp->in_bts;