abis_rsl_rx_dchan(): guard against lchan_lookup() returning NULL

Found this by coincidence, no actual failure case was observed.

lchan_lookup() does have a return NULL code path, so we should not blindly use
its returned pointer.

Change-Id: I34ce126d36420b8194c88c0faa865294334a6658
1 file changed
tree: c9c5df9a5461cb2461a5fb72f3dcf8f20b7e0d2f
  1. contrib/
  2. debian/
  3. openbsc/
  4. .gitignore
  5. .gitreview
  6. .mailmap