document why ipa chopped ping fails with control interface

We cannot test the control interface with an IPA ping message.
The control interface only supports osmocom-specific extensions,
and the IPA ping message is not part of those extensions.
Other tests will have to be devised for the control interface.

Change-Id: Iae0f16394c78196de621c14b34d1b1905c0cb7c8
Related: OS#2010
diff --git a/bsc/BSC_Tests.ttcn b/bsc/BSC_Tests.ttcn
index 28ade1e..9a85a1f 100644
--- a/bsc/BSC_Tests.ttcn
+++ b/bsc/BSC_Tests.ttcn
@@ -2731,8 +2731,9 @@
 }
 
 testcase TC_chopped_ipa_ping() runs on test_CT {
-	const Integers bsc_ipa_ports := {mp_bsc_rsl_port, mp_bsc_oml_port
-					 /* TOOD: This port is failing: mp_bsc_ctrl_port */ };
+	/* The IPA control interface (mp_bsc_ctrl_port) won't work with this test because the control
+	 * interface only implements IPAC_PROTO_OSMO, while the IPA PING request uses IPAC_PROTO_IPACCESS. */
+	const Integers bsc_ipa_ports := {mp_bsc_rsl_port, mp_bsc_oml_port};
 	for (var integer i := 0; i < lengthof(bsc_ipa_ports); i := i + 1) {
 		IPA_Testing.f_run_TC_chopped_ipa_ping(mp_bsc_ip, bsc_ipa_ports[i], CONNECT_TO_SERVER);
 	}