msc: CC SETUP MT speech: verify bearer capabilities
Verify that the MSC sends the bearer capability IE from 3GPP TS 24.008 § D.1.2 for speech in the network to MS direction, instead of allowing e.g. what osmo-msc master and latest release currently do:
- Filling out radio channel requirement the same way as the MS to Network direction, which is wrong for the Network to MS direction: "Bits 6 and 7 are spare bits. The sending side (i.e. the network) shall set bit 7 to value 0 and bit 6 to value 1." (3GPP TS 24.008 Table 10.5.102)
- Sending a speech list in the Network to MS direction, which seems to be allowed in theory and MS are supposed to ignore it (end of Table 10.5.103) but causes bugs in some MS in practice. Therefore it is better to ensure that osmo-msc does not send it (OS#6656).
Implement this in f_mt_call_complete(), which gets used e.g. by TC_lu_and_mt_call.
