bsc: replace TC_assignment_fr_a5_4 with TC_assignment_fr_a5_not_sup

reasons:

* TC_assignment_fr_a5_4() runs an unusual sequence of messages: it first
  fully assigns an lchan, and after that sends a Cipher Mode Command.
  Usually, the ciphering happens as part of attaching (Compl L3).
  The new test TC_assignment_fr_a5_not_sup() does the ciphering in the
  usual sequence, and properly expects a Cipher Mode Reject.

* TC_assignment_fr_a5_4 means to ask for an *unsupported* encryption
  algo. Since we are going to introduce A5/4 support shortly, we'll need
  to free up this name, for a successful A5/4 encryption test.

New test TC_assignment_fr_a5_not_sup() asks for A5/5 encryption, which
is not supported.

Related: SYS#5324
Change-Id: I83eca18d1b3d8d58177aa3750935ec5a3a985ca4
2 files changed