Introduce new callbacks, remember that we have LOC UPD REQ, reject things only once
gsm_data.h add new callbacks, add some parameters, update bsc_hack and
other call sites.
Remember that we need to ACCEPT/REJECT the LOCATION UPDATE REQUEST and
then send the ACCEPT or schedule the sending of the reject. Currently
it is possible that for a new subscriber that we do not have a !subscbr
yet, we will trigger an IDENTITY REQUEST and schedule the reject timer.
This may lead to rejecting AND accepting (a new subscriber). This issue
is triggered when allowing everyone to connect to the network.