RSSI threshold for PUSCH & PUCCH power control

To prevent ADC railing or "clipping" when the received power is too
large, introduce RSSI threshold parameters for PUSCH and PUCCH, which
are now configured in units of 0.1 dB. Here is how you can configure and
use these thresholds:

1. Configuration:
   - Set the pusch_RSSI_Threshold and pucch_RSSI_Threshold parameters in
     your configuration file (e.g., gnb.conf) (MACRLC section).
   - These parameters define the maximum acceptable RSSI values for
     PUSCH and PUCCH, respectively. The unit is either dBm or dBFS,
     depending on the RSSI reporting configuration.

2. Usage:
   - The nr_limit_tpc function will automatically adjust the Transmit
     Power Control (TPC) commands based on the configured RSSI
     thresholds.
   - If the RSSI exceeds the threshold, the TPC command will be limited
     to prevent further increase in power, thereby avoiding ADC
     clipping.