HEADS UP: openbsc.git: force push on master

Today, gerrit has merged four of my changesets twice for some reason (even though they had the very same Change-Id), meaning that openbsc.git master got four empty commits.

It could end up being a stupid thing to do, but I thought if at all then right now and no later: I forced master HEAD back so that we don't have empty commits in it, back to d1c0e3755f2832270a16bdb2d350463409cad887.

I apologize in advance for any inconvenience caused. If you need help to recover from a diverged master branch, don't hesitate to ask!

~Neels