Merge remote-tracking branch 'origin/ifft-avoidance' into integration_2025_w14_p2 (!3276)

Optimization for unused symbols in NR UE

After processing TX frequency domain data skip IFFT call for symbols
that aren't used, the time domain buffer is memset instead.

Biggest benefit is when UE does not transmit PUSCH, or PUSCH is using <
14 symbols

executables/nr-ue.c

@@ -553,9 +553,6 @@ static void RU_write(nr_rxtx_thread_data_t *rxtxD, bool sl_tx_action)
 
   int tmp = openair0_write_reorder(&UE->rfdevice, writeTimestamp, txp, writeBlockSize, fp->nb_antennas_tx, flags);
   AssertFatal(tmp == writeBlockSize, "");
-
-  for (int i = 0; i < fp->nb_antennas_tx; i++)
-    memset(txp[i], 0, writeBlockSize);
 }
 
 void processSlotTX(void *arg)