Validate the choosen UTRAN encryption algorithm

RANAP Security Command can include an encryption IE. If it includes
it the RNC can still ignore it (e.g. unsupported encryption) and
return the Security Command Complete with an choosen encryption IE:
"no encryption".
Validate the encryption element and ensure the encryption is included in
the encryption mask.

Closes: OS#4144
Change-Id: Icfc135c8b8ae862defe7114db492af600c26407f
8 files changed