nanobts: Do not crash on an invalid TRX number

In case the specified trx number is not configured, do not crash
but return NULL from the function. The libosmo-abis library should
close the connection for us then.
1 file changed
tree: 136ca4eac922d17f21402c3be34b527949616811
  1. debian/
  2. hlrsync/
  3. linux-kernel/
  4. openbsc/
  5. wireshark/
  6. README