gprs_gmm: reintroduce calling gsm48_gmm_authorize when not handling GMM Attach Requests

A security command is part of multiple procedures to ensure
integrity (optional also encryption) between MS and RNC.
It should be used for all Iu connections once.
With the rewrite of the GMM Attach FSM the use of the security command
procedure was broken for all procedures e.g. Service Request except GMM
Attach Request.

Relates: OS#3920
Change-Id: I50e8e316f06ae1a6171a6b07e4e2f0761322b779
1 file changed