[gprs] BSSGP: Fix null pointer dereference

Zecke has found this using "make CC="clang --analyze"
1 file changed
tree: cfea9c1a0f892e8c392f609f6f55bdcf1af62217
  1. hlrsync/
  2. linux-kernel/
  3. openbsc/
  4. wireshark/