mgcp_protocol: remove unused variable

The function allocate_port() has pointer a variable end, it even does an
OSMO_ASSERT on it, but it never uses it. Lets remove it.

Change-Id: I369361389c6276e5511c683ebd630093713bdd37
diff --git a/src/libosmo-mgcp/mgcp_protocol.c b/src/libosmo-mgcp/mgcp_protocol.c
index f2fc20c..bc96462 100644
--- a/src/libosmo-mgcp/mgcp_protocol.c
+++ b/src/libosmo-mgcp/mgcp_protocol.c
@@ -370,13 +370,10 @@
 static int allocate_port(struct mgcp_endpoint *endp, struct mgcp_conn_rtp *conn)
 {
 	int i;
-	struct mgcp_rtp_end *end;
 	struct mgcp_port_range *range;
 	unsigned int tries;
 
 	OSMO_ASSERT(conn);
-	end = &conn->end;
-	OSMO_ASSERT(end);
 
 	range = &endp->cfg->net_ports;