msc: cipher mode: move cipher expect to new function

Move the ciphering calculations from f_mm_common() to new function
f_get_expected_encryption(), so that it can be re-used for ciphering in
inter-BSC handover (upcoming patch).

Add tr_BSSMAP_CipherModeCmd2() to conveniently use the values returned
by f_get_expected_encryption().

To verify the Ciphering Mode Command in f_mm_common(), use the new
tr_BSSMAP_CipherModeCmd2(), and rely on template matching instead of
checking each IE individually.

Related: SYS#5324
Change-Id: I1f775889fb801d441ea6c8b0f0c34718b814c09e
2 files changed