osmo-bts-trx: clarify check_transceiver_availability()
seem to be an important step in OML communication. Their main purpose is to send OML
states after receiving a Set BTS Attributes message.
However, they are named for their peculiar side-purpose to delay this step
in case the transceiver has not sent the first clock yet.
Also, it is clear that if the function were called twice, it would send Disabled
states for the RADIO-CARRIER and CHANNEL objects every time, without really
checking the transceiver availability.
Particulary, an erratic BSC might send a Set BTS Attributes out of sequence,
which would cause above OML objects to change to Disabled state immediately.
This is in need of clarification:
- rename the functions
- implement saner logic to detect availability transitions
- comment lusciously