Fix EMA cold-start for noise and SNR/RSSI measurements
Initialize n0_subband_power and power control avg_snr/avg_rssi directly
from the first measurement instead of starting from zero.
Starting from zero causes the EMA to converge slowly, leading to
underestimated noise power at gNB startup. This results in inflated SNR
estimates, which triggers UE uplink power ramp-up, antenna saturation,
and a positive feedback loop of increasing noise.
Jaroslava Fiedlerova
93df326273