RBS2000: Avoid segfault if ts->lapd instance doesn't exist

This happens e.g. with DAHDI driver, when the DAHDI device cannot be
opened.  Let's not prematurely seg-fault early in the RBS2000 signal
handler, but take the proper error handlign for this.

Change-Id: I9223fb1568d3db7e278f07240c4be334c6602a13
1 file changed
tree: 9a18bfb8878dad82b5af06e6cac9c2b323b0781d
  1. contrib/
  2. debian/
  3. openbsc/
  4. .gitignore
  5. .gitreview
  6. .mailmap