bsc: add TC_ciph_mode_a5_2_1

Verify that A5/1 is preferred over A5/2. Add encr_exp_enc_alg to
MSC_ConnectionHandler:TestHdlrEncrParams, so the expected encryption
algorithm can be different from what the MSC tells the BSC about the
capabilities of MS.

Related: OS#4975
Change-Id: I688d056bcfe73f7846f908a28f4621f944cf2178
3 files changed