MGCP_Test: Clean up after TC_crcx_sdp

The testcase TC_crcx_sdp does not clean up the connection it
created. This can cause subsequent tests to fail.

- Use f_dlcx_ok() to clean up the connection once the test
  is done.

Change-Id: I4e0f5ce218fadc5debe0bbf548b69919584ab66c

mgw/MGCP_Test.ttcn

@@ -388,6 +388,10 @@ module MGCP_Test {
 				  { valueof(ts_SDP_rtpmap(98, "AMR/8000")),
 				    valueof(ts_SDP_ptime(20)) });
 		resp := mgcp_transceive_mgw(cmd, tr_CRCX_ACK);
+
+		/* clean-up */
+		f_dlcx_ok(ep, call_id);
+
 		setverdict(pass);
 	}