fix(nr_dlsch): symbol offset calculation

There was an indexing error in the calculation of the symbol offset `re_beginning_of_symbol`.
The symbol was tested to hold PTRS or DMRS based on the index of the
first symbol processed in the task and not based on the index of the
symbol as it should be.
Then PDSCH generation was not working properly for more than one symbol
per task.

openair1/PHY/NR_TRANSPORT/nr_dlsch.c

@@ -743,12 +743,12 @@ static int do_one_dlsch(unsigned char *input_ptr, PHY_VARS_gNB *gNB, NR_gNB_DLSC
     rdata->dlPtrsSymPos = dlPtrsSymPos;
     rdata->n_ptrs = n_ptrs;
     rdata->beam_nb = beam_nb;
-    for (int s = 0; s < rdata->numSymbols; s++) {
-      rdata->re_beginning_of_symbol[l_symbol + s] = re_beginning_of_symbol;
+    for (int s = l_symbol; s < l_symbol + rdata->numSymbols; s++) {
+      rdata->re_beginning_of_symbol[s] = re_beginning_of_symbol;
       re_beginning_of_symbol += rel15->rbSize * NR_NB_SC_PER_RB;
-      if (n_ptrs > 0 && is_ptrs_symbol(l_symbol, dlPtrsSymPos)) {
+      if (n_ptrs > 0 && is_ptrs_symbol(s, dlPtrsSymPos)) {
         re_beginning_of_symbol -= n_ptrs;
-      } else if (rel15->dlDmrsSymbPos & (1 << l_symbol)) {
+      } else if (rel15->dlDmrsSymbPos & (1 << s)) {
         re_beginning_of_symbol -= n_dmrs;
       }
     }