According to 3GPP TS 25.413 8.26.2.2, "The RNC shall include the Global
RNC-ID IE in the RESET message." To be able to do that, osmo-hnbgw needs
to know the local PLMN.
Introduce explicit knowledge of the local PLMN by config, and use this
configured local PLMN in places where the local PLMN was so far derived
otherwise.
Subsequent patches will separately add the RNC-ID to the RANAP RESET
messages.
Since the PLMN is required to send correct RESET and RESET ACK, include
the new 'plmn' config item in all example configurations.
Related: SYS#6441
Change-Id: If404c3859acdfba274c719c7cb7d16f97d831a2a
Andreas Eversberg
Neels Hofmeyr