sysmobts: Free the message on older firmware releases
sysmobts: Free the message on older firmware releases

Seen while implementing a new functionality in the code.

osmocom/osmo-bts,telenoobie/osmo-bts,geosphere/osmo-bts,osmocom/osmo-bts,geosphere/osmo-bts,geosphere/osmo-bts,telenoobie/osmo-bts,geosphere/osmo-bts,osmocom/osmo-bts,telenoobie/osmo-bts,telenoobie/osmo-bts