BTS: fix latest: ignore mismatching messages in as_rsl_init_guard()

Another surprise from the latest osmo-bts release: it may send us
CCCH LOAD INDication message during the RSL bring up. Ignore it.

Change-Id: Iab22b620a5f7b07fe03c1b13bebef2931d14879d
diff --git a/bts/BTS_Tests.ttcn b/bts/BTS_Tests.ttcn
index 012327e..b098fc6 100644
--- a/bts/BTS_Tests.ttcn
+++ b/bts/BTS_Tests.ttcn
@@ -188,6 +188,8 @@
 		Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
 			"Timeout waiting for RSL bring up");
 		}
+	/* osmo-bts may send us CCCH LOAD INDication or whatever else */
+	[] RSL_CCHAN.receive(ASP_RSL_Unitdata:?) { repeat; }
 }
 
 function f_init_rsl(charstring id) runs on test_CT {