gscon: pick suitable payload type / encoding name for MGCP

The GSCON FSM does not care about the codec information when performing
interactions with the MGW. Before upgrading the client the codec
information was hardcoded to AMR inside the client. Now the client
offers APIs to set the codec information. Since this feature is new,
osmo-bsc does not set any codec information yet, which causes many of
the TTCN3 tests to fail. So lets add some logic to pick suitable codec
info.

- Hardcode ptime to 20 (is the same for all possible codecs)
- Select a codec according to the flags in userplane

Change-Id: Ibddc3492572b39f166e3a1b8b8120813ce2dadc2
Related: OS#2728
1 file changed