[SGSN] Fix segfault when doing PS PAGING

The 'bssgp_paging_info' contains a pointer to the P-TMSI, and not
the P-TMSI itself.  The reason is that it is an optional BSSGP IE.
1 file changed
tree: f6a8586260e1b3fcaccc546bb52ff42678657f1a
  1. hlrsync/
  2. linux-kernel/
  3. openbsc/
  4. wireshark/