According to 3GPP TS 24.008 § 4.7.1.2 some GMM frames are not supposed
to be ciphered. Propagate information about the necessity for
encryption between MM <-> LLC to ensure only proper frames are
encrypted/decrypted/dropped.
Change-Id: I0358905e60d1b182f75caec81bfcc72bbbbb2aa1
Related: OS#1582