lms: Fail in case of unsupported configuration
lms: Fail in case of unsupported configuration

There might be some configuration that's not supported by osmo-bts-lms,
and we should reject that properly.

Change-Id: I6f82edce589030a4407f6150fb7e8abe6417c1f2
Closes: OS#3347

osmocom/osmo-trx,ttsou/osmo-trx,osmocom/osmo-trx,ttsou/osmo-trx,osmocom/osmo-trx,ttsou/osmo-trx,ttsou/osmo-trx,osmocom/osmo-trx