* separate the LLME and LLE state in the LLC layer
* introduce gprs_llgmm_assign() function for LLGMM-ASSIGN.req primitive
* change QoS profile to match 'real' SGSN
* Update the new TLLI when assigning a P-TMSI
The result now is that the LLC layer is notified of TLLI changes, which in turn
means it doesn't allocate a new LLE structure every TLLI change, which again
in turn means that the UI frame sequence number does not reset to zero.
As a result, MS should no longer ignore frames based on wrong UI sequence number.
Our state transitions and timers now reflect 04.08 for GMM much
better than before. Also, we allocate a new P-TMSI on every ATTACH
and RA UPDATE, as some phones seem to get confused if they don't
get a P-TMSI.
* store LLC SAPI as part of PDP ctx
* store NSEI + BVCI as part of MM ctx
* export gsm48_tx_gsm_act_pdp_acc() and call it from sgsn_libgtp.c
* create and use gsm48_tx_gsm_act_pdp_rej for error cases
* print SAPI as part of VTY show pdp
libgtp of the OpenGGSN project will allow us to speak the GTPv0/v1
protocol of the interface between SGSN and GGSN.
This commit includes code for the main libgtp integration (file
descriptor, select loop, timer) as well as code to encode/send
a CREATE PDP CONTEXT request.