The E_(P)MM_IMPLICIT_DETACH event was actually sent and handled when the
UE was considered to be detached, no matter the reason, be it due to
implicit detach, or Detach Request received, etc.
So, let's properly name the event to avoid confusions in the code.
Related: SYS#5389
Change-Id: I224ea9db80b4d96696934cea06349dab036f919b
Implement TS 23.060 6.1.1 Mobility Management States (A/Gb mode) using
osmocom FSM and drop old implementation.
Most of the logic on each state is still kept in gprs_gmm.c, will be
inserted into the FSM later.
Change-Id: I04004423e993107374d5a3549b8a93ac169251dd