Once we get RF-ACTIVATE.conf from L1, we now enable the corresponding
LED. We also switch it off on RF-DEACTIVATE.conf. We do _not_ switch
it off when osmo-bts crashes or terminates before RF-DEACTIVATE.conf.
The latter is intentional, as RF may very well still be active at that
point. The re-spawning script will re-set the DSP and therby turn off
the RF and then disable the LED.
A better solution might be to do all this in the kernel driver for the
DSP.
