osmo-bts-omldummy is used as the OML backend in the ttcn3-bsc-test. The common OML code encodes bts->support.* and trx->support.* fields verbatim into the IPA Supported Features IE (NM_ATT_IPACC_SUPP_FEATURES) in Get Attributes Responses. Since bts_model_init() and bts_model_trx_init() never initialized these fields, they were reported as all-zeros to osmo-bsc.
osmo-bsc now inspects the supported channel modes before activating a channel. An all-zero chan_modes value (present but no bits set) causes osmo-bsc to reject every speech mode, breaking all assignment-related TTCN-3 test cases.
Initialize ciphers, gprs_codings, freq_bands, chan_types and chan_modes to sensible values, matching what osmo-bts-virtual does, so that osmo-bts-omldummy reports its capabilities correctly.
