If we receive one of those strange BS-11 "Cause 22" errors, we don't need
to check if the lchan use counter is > 0. If it was 0, the lchan gets
released anyway.
This was proposed by Andreas Eversberg. I made it conditional on the T200
timer expired cause, as I'm not sure if we really should give up that quickly
on other errors such as just simply receiving an unsolicited response.
* add bts->band field plus corresponding VTY and commandline argument
* add trx->nominal_power and trx->max_power_red fields
* add rsl_chan_bs_power_ctrl() to control TRX RF power for a given TS
* add rsl_chan_ms_power_ctrl() to control MS RF power for a given lchan.