msc: Only unregister the fd if the fd value is valid.

This makes sure that someone can call bsc_msc_lost multiple times
even if there is no MSC connection. This makes sense as bsc_msc_lost
is public and be called from client code.
1 file changed
tree: d8d5f1b21531ba55c1e3f985cf0348f89bffa58a
  1. hlrsync/
  2. linux-kernel/
  3. openbsc/
  4. wireshark/