TC_sabm_invalid_resp BTS_Tests_LAPDm

Regression

Failing for the past 1 build since #88

Took 33 sec (from Titan)

Stack Trace

"BTS_Tests.ttcn:732 : Tguard timeout"
      BTS_Tests_LAPDm.ttcn:1481 BTS_Tests_LAPDm control part
      BTS_Tests_LAPDm.ttcn:379 TC_sabm_invalid_resp testcase