assignment_fsm: only include speech codec (choosen) on AoIP networks

The field speech codec (choosen) in the ASSIGNMENT COMPLETE message
has been specified with AoIP. Since sccp-lite has been specified before
AoIP, we should not include the speech codec (choosen) field in the
ASSIGNMENT COMPLETE, when osmo-bsc is connected to an sccp-lite based
network.

- make sure speech codec (choosen) is only included on AoIP based
  networks

Change-Id: Ic7f28aacc953d96ebf3aa04f3e1810475458c1a8
1 file changed