Clean-up nr_slot_fep

1.Create new funtion nr_symbol_fep() to do OFDM demod of one symbol on
  all antennas. This is called by nr_slot_fep() for now. In the
  upcoming MR, this function will be called directly after reading
  each OFDM symbol from the radio.

2.Removed redundant memory alignment. DFT function performs memory
  alignment if the input memory is not aligned.

openair1/SIMULATION/NR_PHY/ulsim.c

@@ -1468,14 +1468,14 @@ int main(int argc, char *argv[])
         }
         int offset = (slot & 3) * gNB->frame_parms.symbols_per_slot * gNB->frame_parms.ofdm_symbol_size;
         for (int aa = 0; aa < gNB->frame_parms.nb_antennas_rx; aa++)  {
-          apply_nr_rotation_RX(&gNB->frame_parms,
-                               gNB->common_vars.rxdataF[0][aa],
-                               gNB->frame_parms.symbol_rotation[1],
-                               slot,
-                               gNB->frame_parms.N_RB_UL,
-                               offset,
-                               0,
-                               gNB->frame_parms.Ncp == EXTENDED ? 12 : 14);
+          const unsigned int max_symb = (gNB->frame_parms.Ncp == EXTENDED) ? 12 : 14;
+          for (int sym = 0; sym < max_symb; sym++)
+            apply_nr_rotation_symbol_RX(&gNB->frame_parms,
+                                        gNB->common_vars.rxdataF[0][aa] + offset + sym * gNB->frame_parms.ofdm_symbol_size,
+                                        gNB->frame_parms.symbol_rotation[1],
+                                        gNB->frame_parms.N_RB_UL,
+                                        slot,
+                                        sym);
         }
 
         ul_proc_error = phy_procedures_gNB_uespec_RX(gNB, frame, slot, &UL_INFO);