Sync protocol with OsmoPCU
Sync protocol with OsmoPCU

Copy-paste changes from OsmoPCU commit 0a8fae8d141c2cfa4387ffe9b35402d5b8cc85cd.

Change-Id: I15e6cc86604947a173e8675ba4b41a3bda2d3296

osmocom/osmo-bts,osmocom/osmo-bts,osmocom/osmo-bts