context_map_sccp: Fix assert hit due to missing ev handlingThis was being triggered recently byHNBGW_Tests.TC_ranap_cs_mo_disconnect in osmo-ttcn3-hacks.git.Change-Id: Idaad11eaa3c2e56de792f80bab1f1d8435ef9b68(cherry picked from commit 0e987d7f3c714bea237beb8c72d70103cbf65031)