Introduce logical updating request operation on the gsm_lchan

We are going to have logical operations like Phone Call, SMS,
Paging, Updating Request on a logical channel and for each of
these operations we might need to store state. For now pointers
in gsm_lchan look like the best way of doing this and we start
by introducing an operation for the location updating request.

The new flow of things are:
    - We get the location updating request and update/create
      the subscriber and maybe send the identity requests to
      the mobile station
    - We start the updating timer, if it times out we will
      reject the mobile station.
    - Once we get the Identity Responses we have asked for
      and the reject timer did not fire yet we might accept
      the user.
tree: 69a6060c83a63decd910172a66e3f85f96c5b0a0
  1. tests/
  2. tools/
  3. AUTHORS
  4. configure.in
  5. COPYING
  6. Makefile.am
  7. README